力扣-15.三数之和

题目链接

15.三数之和

class Solution {public List<List<Integer>> threeSum(int[] nums) {List<List<Integer>> res = new ArrayList<>();Arrays.sort(nums);for (int i = 0; i < nums.length - 2; i++) {if (nums[i] > 0)break;if (i > 0 && nums[i] == nums[i - 1])continue;int left = i + 1;int right = nums.length - 1;while (left < right) {int sum = nums[i] + nums[left] + nums[right];if (sum > 0) {right--;} else if (sum < 0) {left++;} else {res.add(Arrays.asList(nums[i], nums[left], nums[right]));while (left < right && nums[left] == nums[left + 1]) {left++;}while (left < right && nums[right] == nums[right - 1]) {right--;}left++;right--;}}}return res;}
}

小结：排序+双指针，注意去重和剪枝操作，还有Arrays.sort()与Arrays.asList()的使用。