思路
我的思路,先排序,循环确定前两个值,最后一个值二分
看了题解:
最后两个值可以使用双指针,因为是有序的,而且是求和
注意重复值:
public List<List<Integer>> threeSum(int[] nums) {Arrays.sort(nums);List<List<Integer>> resultList = new ArrayList<>();for (int i = 0; i < nums.length-2; i++) {if (i!=0 && nums[i] == nums[i-1]){continue;}resultList.addAll(twoSum(i+1, nums[i],nums));}return resultList;}private List<List<Integer>> twoSum(int index, int first, int[] nums) {List<List<Integer>> resultList = new ArrayList<>();int left = index;int right = nums.length-1;while (left<right){if (nums[left] + nums[right] + first == 0){List<Integer> list = new ArrayList<>(3);list.add(first);list.add(nums[left]);list.add(nums[right]);resultList.add(list);left = findNext(left,nums);} else if (nums[left] + nums[right] + first >0) {right--;}else {left++;}}return resultList;}//避免出现重复,如果右移和右边一样private int findNext(int left, int[] nums) {int index = left+1;while (index < nums.length &&nums[index] == nums[left]){index++;}return index;}```