Added code for contest 106

varunu28 · varunu28 · commit ec8b5a8ae99b · 2018-10-14T07:30:59.000-07:00
diff --git a/Contests/Weekly Contest 106/3Sum With Multiplicity.java b/Contests/Weekly Contest 106/3Sum With Multiplicity.java
@@ -0,0 +1,31 @@
+class Solution {
+    public int threeSumMulti(int[] A, int target) {
+        int div = 1000000007;
+        int count = 0;
+        for (int i=0; i<A.length; i++) {
+            int temp = getPairsCount(A.length, target-A[i], A, i+1);
+            count = (count+temp)%div;
+        }
+        return count;
+    }
+
+    public int getPairsCount(int n, int sum, int[] arr, int start) {
+        Map<Integer, Integer> map = new HashMap<>();
+        for (int i=start; i<n; i++) {
+            map.put(arr[i], map.getOrDefault(arr[i], 0)+1);
+        }
+
+        int count = 0;
+        for (int i=start; i<n; i++) {
+            if(map.get(sum-arr[i]) != null) {
+                count += map.get(sum - arr[i]);
+            }
+
+            if (sum-arr[i] == arr[i]) {
+                count--;
+            }
+        }
+
+        return count/2;
+    }
+}
diff --git a/Contests/Weekly Contest 106/Minimum Add to Make Parentheses Valid.java b/Contests/Weekly Contest 106/Minimum Add to Make Parentheses Valid.java
@@ -0,0 +1,24 @@
+class Solution {
+    public int minAddToMakeValid(String S) {
+        Stack<Character> open = new Stack<>();
+        int count = 0;
+
+        for (char c : S.toCharArray()) {
+            if (c == '(') {
+                open.push(c);
+            }
+            else {
+                if (open.empty()) {
+                    count++;
+                }
+                else {
+                    open.pop();
+                }
+            }
+        }
+
+        count += open.size();
+
+        return count;
+    }
+}
diff --git a/Contests/Weekly Contest 106/Sort Array By Parity II.java b/Contests/Weekly Contest 106/Sort Array By Parity II.java
@@ -0,0 +1,35 @@
+class Solution {
+    public int[] sortArrayByParityII(int[] A) {
+        int[] ans = new int[A.length];
+        int[] odd = new int[A.length/2];
+        int[] even = new int[A.length/2];
+
+        int i = 0;
+        int j = 0;
+        int k = 0;
+
+        while (k < A.length) {
+            if (A[k]%2 == 0) {
+                even[j++] = A[k++];
+            }
+            else {
+                odd[i++] = A[k++];
+            }
+        }
+        
+        i = 0;
+        j = 0;
+        k = 0;
+
+        while (k < ans.length) {
+            if (k%2 == 0) {
+                ans[k++] = even[j++];
+            }
+            else {
+                ans[k++] = odd[i++];
+            }
+        }
+
+        return ans;
+    }
+}
