Hot10015. 三数之和

Posted 2022-07-01 王六六的IT日常

15. 三数之和
中等题

👉两数之和

排序+ 双指针
参考题解：https://leetcode.cn/problems/3sum/solution/3sumpai-xu-shuang-zhi-zhen-yi-dong-by-jyd/

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