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chenweijie
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add test
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16 files changed

+517
-7
lines changed

16 files changed

+517
-7
lines changed

‎src/main/java/com/chen/algorithm/study/test121/Solution3.java

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package com.chen.algorithm.study.test121;
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import org.junit.Test;
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/**
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* 双指针算法
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*
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* @author : chen weijie
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* @Date: 2019-11-01 23:54
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*/
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public class Solution3 {
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public int maxProfit(int[] prices) {
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if (prices == null || prices.length == 0) {
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return 0;
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}
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int min = Integer.MAX_VALUE;
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int max = 0;
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for (int price : prices) {
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min = Math.min(price, min);
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max = Math.max(max, price - min);
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}
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return max;
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}
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@Test
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public void testCase() {
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int[] n = {7, 6, 4, 3, 1};
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System.out.println(maxProfit(n));
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}
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}

‎src/main/java/com/chen/algorithm/study/test122/Solution2.java

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package com.chen.algorithm.study.test122;
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/**
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* @author : chen weijie
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* @Date: 2020-05-16 23:36
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*/
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public class Solution2 {
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public static int maxProfit(int[] prices) {
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if (prices == null || prices.length == 0) {
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return 0;
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}
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int sum = 0;
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for (int i = 1; i < prices.length; i++) {
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if (prices[i - 1] < prices[i]) {
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sum = sum + (prices[i] - prices[i - 1]);
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}
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}
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return sum;
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}
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public static void main(String[] args) {
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int[] n = {7, 1, 5, 3, 6, 4};
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System.out.println(maxProfit(n));
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}
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}

‎src/main/java/com/chen/algorithm/study/test15/Solution2.java

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package com.chen.algorithm.study.test15;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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/**
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* @author : chen weijie
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* @Date: 2020-05-22 01:50
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*/
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public class Solution2 {
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public List<List<Integer>> threeSum(int[] nums) {
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List<List<Integer>> res = new ArrayList<>();
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if (nums == null || nums.length == 0) {
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return res;
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}
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Arrays.sort(nums);
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for (int i = 0; i < nums.length; i++) {
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if (nums[i] > 0) {
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break;
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}
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if (i > 0 && nums[i] == nums[i - 1]) {
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continue;
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}
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int L = i + 1, R = nums.length - 1;
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while (L < R) {
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int sum = nums[i] + nums[L] + nums[R];
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if (sum == 0) {
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res.add(Arrays.asList(nums[i], nums[L], nums[R]));
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while (L < R && nums[L] == nums[L + 1]) {
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L++;
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}
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while (L < R && nums[R] == nums[R - 1]) {
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R--;
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}
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L++;
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R--;
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} else if (sum > 0) {
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R--;
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} else {
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L++;
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}
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}
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}
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return res;
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}
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}

‎src/main/java/com/chen/algorithm/study/test160/Solution1.java

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@@ -39,7 +39,7 @@ public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
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pB = headA;
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}
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}
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return null;
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return pB;
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}
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‎src/main/java/com/chen/algorithm/study/test2/Solution2.java

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package com.chen.algorithm.study.test2;
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import org.junit.Test;
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/**
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* @author : chen weijie
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* @Date: 2019-09-07 16:16
@@ -33,8 +35,34 @@ public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
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}
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return dummmy.next;
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}
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@Test
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public void testCase() {
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ListNode l1_1 = new ListNode(2);
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ListNode l1_2 = new ListNode(4);
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ListNode l1_3 = new ListNode(3);
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l1_1.next = l1_2;
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l1_2.next = l1_3;
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ListNode l2_1 = new ListNode(5);
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ListNode l2_2 = new ListNode(6);
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ListNode l2_3 = new ListNode(4);
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l2_1.next = l2_2;
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l2_2.next = l2_3;
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ListNode result = addTwoNumbers(l1_1, l2_1);
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System.out.println(result.val);
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System.out.println(result.next.val);
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System.out.println(result.next.next.val);
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}
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}

‎src/main/java/com/chen/algorithm/study/test206/Solution3.java

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@@ -15,14 +15,15 @@ public ListNode reverseList(ListNode head) {
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return head;
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}
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ListNode pre = null;
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ListNode dummy = new ListNode(-1);
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dummy.next = head;
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while (head != null) {
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ListNode temp = head.next;
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head.next = pre;
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pre = head;
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head.next = dummy;
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dummy = head;
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head = temp;
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}
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return pre;
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return dummy;
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}
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‎src/main/java/com/chen/algorithm/study/test24/Solution2.java

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package com.chen.algorithm.study.test24;
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/**
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* 给定一个链表，两两交换其中相邻的节点，并返回交换后的链表。
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* <p>
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* 你不能只是单纯的改变节点内部的值，而是需要实际的进行节点交换
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*
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* @author : chen weijie
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* @Date: 2020-05-03 11:27
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*/
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public class Solution2 {
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public ListNode swapPairs(ListNode head) {
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if (head == null) {
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return null;
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}
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ListNode dummy = new ListNode(-1);
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dummy.next = head;
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ListNode prev = dummy;
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while (head != null && head.next != null) {
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ListNode firstNode = head;
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ListNode secondNode = head.next;
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firstNode.next = secondNode.next;
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secondNode.next = firstNode;
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prev.next = secondNode;
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prev = firstNode;
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head = firstNode.next;
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}
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return dummy.next;
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}
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}

‎src/main/java/com/chen/algorithm/study/test3/Solution.java

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@Test
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public void testCase() {
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System.out.println(lengthOfLongestSubstring("cdfg"));
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System.out.println(lengthOfLongestSubstring("cdfcg"));
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}
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‎src/main/java/com/chen/algorithm/study/test300/Solution2.java

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package com.chen.algorithm.study.test300;
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import org.junit.Test;
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/**
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* https://leetcode-cn.com/problems/longest-increasing-subsequence/solution/zui-chang-shang-sheng-zi-xu-lie-dong-tai-gui-hua-2/
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*
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* @author : chen weijie
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* @Date: 2019-12-22 16:28
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*/
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public class Solution2 {
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public int lengthOfList(int[] nums) {
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if (nums == null || nums.length == 0) {
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return 0;
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}
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int[] dp = new int[nums.length];
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dp[0] = 1;
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int max = 1;
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for (int i = 1; i < dp.length; i++) {
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int tem = 0;
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for (int j = 0; j < i; j++) {
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if (nums[j] < nums[i]) {
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tem = Math.max(tem, dp[j]);
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}
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}
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dp[i] = tem + 1;
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max = Math.max(dp[i], max);
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}
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return max;
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}
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@Test
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public void testCase() {
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int[] n = {4, 1, -4, 7, -2, 9, 0};
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System.out.println(lengthOfList(n));
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}
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}

‎src/main/java/com/chen/algorithm/study/test322/Solution.java

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package com.chen.algorithm.study.test322;
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import org.junit.Test;
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import java.util.Arrays;
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/**
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* https://leetcode-cn.com/problems/coin-change/solution/322-ling-qian-dui-huan-by-leetcode-solution/
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*
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* @author : chen weijie
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* @Date: 2020-05-24 00:43
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*/
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public class Solution {
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public int coinChange(int[] coins, int amount) {
16+
int max = amount + 1;
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int[] dp = new int[amount + 1];
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Arrays.fill(dp, max);
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dp[0] = 0;
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for (int i = 0; i < dp.length; i++) {
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for (int coin : coins) {
22+
if (coin <= i) {
23+
dp[i] = Math.min(dp[i], dp[i - coin] + 1);
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}
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}
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}
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return dp[amount] > amount ? -1 : dp[amount];
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}
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@Test
32+
public void testCase() {
33+
int[] coins = {2};
34+
System.out.println(coinChange(coins, 3));
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}
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}

‎src/main/java/com/chen/algorithm/study/test50/Solution3.java

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package com.chen.algorithm.study.test50;
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/**
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* @author : chen weijie
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* @Date: 2020-05-22 02:52
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*/
7+
public class Solution3 {
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public double myPow(double x, int n) {
11+
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13+
if (n < 0) {
14+
x = 1 / x;
15+
n = -n;
16+
}
17+
return quick(x, n);
18+
}
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public double quick(double x, int n) {
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23+
if (n == 0) {
24+
return 1d;
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}
26+
double y = quick(x, n / 2);
27+
return n % 2 == 0 ? y * y : y * y * x;
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}
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}

‎src/main/java/com/chen/algorithm/study/test674/Solution.java

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package com.chen.algorithm.study.test674;
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/**
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* @author : chen weijie
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* @Date: 2020-05-24 00:15
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*/
7+
public class Solution {
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public int findLengthOfLCIS(int[] nums) {
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11+
if (nums == null || nums.length == 0) {
12+
return 0;
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}
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int[] dp = new int[nums.length];
16+
dp[0] = 1;
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int max = 1;
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for (int i = 1; i < nums.length; i++) {
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if (nums[i] > nums[i - 1]) {
20+
dp[i] = dp[i - 1] + 1;
21+
} else {
22+
dp[i] = 1;
23+
}
24+
max = Math.max(max, dp[i]);
25+
}
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return max;
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}
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}

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