Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.
Note:
- Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c)
- The solution set must not contain duplicate triplets.
For example, given array S = {-1 0 1 2 -1 -4}, A solution set is: (-1, 0, 1) (-1, -1, 2)
先将数组排序，从头开始选择第一个元素，然后在选择剩下的两个元素。public List<List<Integer>> threeSum(int[] num) { List<List<Integer>> list = new ArrayList<List<Integer>>(); Arrays.sort(num); int len = num.length; for (int i = 0; i < len - 2; i++) { if (i == 0 || num[i] != num[i - 1]) { int target = 0 - num[i]; int left = i + 1; int right = len - 1; while (left < right) { if (left < right) { int temp = num[left] + num[right]; if (temp == target) { if (left == i + 1 || num[left] != num [left - 1]) { List<Integer> subList = new ArrayList<Integer>(); subList.add(num[i]); subList.add(num[left]); subList.add(num[right]); list.add(subList); } left++; right--; } else if (temp > target) { right--; } else { left++; } } } } } return list; }
原文地址：http://blog.csdn.net/u010378705/article/details/31470771
