add 4Sum

Author: yangdi

src2/4Sum/4Sum.py

@@ -0,0 +1,25 @@
+'''
+
+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.
+
+Note:
+Elements in a quadruplet (a,b,c,d) must be in non-descending order. (ie, a <= b <= c <= d)
+The solution set must not contain duplicate quadruplets.
+
+ For example, given array S = {1 0 -1 0 -2 2}, and target = 0.
+
+    A solution set is:
+    (-1,  0, 0, 1)
+    (-2, -1, 1, 2)
+    (-2,  0, 0, 2)
+'''
+
+class Solution:
+    # @return a list of lists of length 4, [[val1,val2,val3,val4]]
+    def fourSum(self, num, target):
+        num.sort()
+        return num
+
+if __name__ == '__main__':
+	print Solution().fourSum([1, 0, -1, 0, -2, 2], 0)