New solutions

Author: rahulcode22

Hashing/4-sum.py

@@ -0,0 +1,43 @@
+'''
+Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target.
+'''
+class Solution:
+    # @param A : list of integers
+    # @param B : integer
+    # @return a list of list of integers
+    def fourSum(self, arr, target):
+        i = 0
+        j = 1
+        flag = 0
+        n = len(arr)
+        ans = []
+        if n < 4:
+            return ans
+        arr.sort()
+        while i < n-3:
+            j = i+1
+            while j < n-2:
+                num = target - (arr[i]+arr[j])
+                k = j+1
+                l = n-1
+                while k < l:
+                    sum_ = arr[k]+arr[l]
+                    if sum_ == num:
+                        ans.append([arr[i],arr[j],arr[k],arr[l]])
+                        while arr[k] == arr[k+1] and k < n-2:
+                            k += 1
+                        while arr[l] == arr[l-1] and l > 0:
+                            l -= 1
+                        k += 1
+                        l -= 1
+                    elif sum_ < num:
+                        k += 1
+                    else:
+                        l -= 1
+                while arr[j] == arr[j+1] and j < n-2:
+                    j += 1
+                j += 1
+            while arr[i] == arr[i+1] and i < n-2:
+                i += 1
+            i += 1
+        return ans

Hashing/longest-substring-without-repeat.py

@@ -33,4 +33,3 @@ def lengthOfLongestSubstring(self, A):
             prev_best = min(i-prev[A[i]], prev_best+1)
             best = max(best, prev_best)
         return best
-Close