题目
https://leetcode-cn.com/problems/3sum
解法
固定一个数，两数之和
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| class Solution {
public List<List<Integer>> threeSum(int[] nums) {
if (nums == null || nums.length == 0) {
return new ArrayList<List<Integer>>();
}
Arrays.sort(nums);
int len = nums.length;
List<List<Integer>> res = new ArrayList<List<Integer>>();
for(int first=0; first<len; first++) {
if(first>0 && nums[first] == nums[first-1]) {
continue;
}
int target = -nums[first];
int third = len-1;
for(int second=first+1; second<third; ) {
if(second>first+1 && nums[second] == nums[second-1]) {
second++;
continue;
}
if(second == third) {
break;
}
if(nums[second]+nums[third] == target) {
List<Integer> list = new ArrayList<>();
list.add(nums[first]);
list.add(nums[second]);
list.add(nums[third]);
res.add(list);
second++;
third--;
} else if(nums[second]+nums[third] < target) {
second++;
} else {
third--;
}
}
}
return res;
}
}
|
