Add 0001 Solution

luojing · luojing · commit 93e4b249b12b · 2022-07-15T23:44:32.000+08:00
diff --git a/src/com/blankj/easy/_0001/LJSolution.java b/src/com/blankj/easy/_0001/LJSolution.java
@@ -0,0 +1,54 @@
+import java.util.Arrays;
+import java.util.HashMap;
+
+/**
+ * @author luojing
+ * @description LJSolution
+ * @date 2022/07/15
+ */
+
+public class LJSolution {
+
+    /**
+     * Solution1
+     * @param nums
+     * @param target
+     * @return
+     */
+    public int[] twoSum1(int[] nums, int target) {
+        for (int i = 0; i < nums.length; i++) {
+            for (int j = 0; j < nums.length; j++) {
+                if (nums[i] + nums[j] == target) {
+                    return new int[] {i, j};
+                }
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Solution2
+     * @param nums
+     * @param target
+     * @return
+     */
+    public int[] twoSum2(int[] nums, int target) {
+        int length = nums.length;
+        HashMap<Integer, Integer> map = new HashMap<>();
+        for (int i = 0; i < length; i++) {
+            final Integer value = map.get(nums[i]);
+            if (value != null) {
+                return new int[] { value, i};
+            }
+            map.put(target - nums[i], i);
+        }
+        return null;
+    }
+
+    public static void main(String[] args) {
+        LJSolution ljSolution = new LJSolution();
+        int[] nums = new int[] {2, 7, 11, 15};
+        int target = 9;
+        System.out.println(Arrays.toString(ljSolution.twoSum1(nums, target)));
+    }
+}
