Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

15. 三数之和 #8

Open
webVueBlog opened this issue Sep 9, 2022 · 0 comments
Open

15. 三数之和 #8

webVueBlog opened this issue Sep 9, 2022 · 0 comments

Comments

@webVueBlog
Copy link
Owner

15. 三数之和

Description

Difficulty: 中等

Related Topics: 数组, 双指针, 排序

给你一个整数数组 nums ,判断是否存在三元组 [nums[i], nums[j], nums[k]] 满足 i != ji != kj != k ,同时还满足 nums[i] + nums[j] + nums[k] == 0 。请

你返回所有和为 0 且不重复的三元组。

**注意:**答案中不可以包含重复的三元组。

示例 1:

输入:nums = [-1,0,1,2,-1,-4]
输出:[[-1,-1,2],[-1,0,1]]
解释:
nums[0] + nums[1] + nums[2] = (-1) + 0 + 1 = 0 。
nums[1] + nums[2] + nums[4] = 0 + 1 + (-1) = 0 。
nums[0] + nums[3] + nums[4] = (-1) + 2 + (-1) = 0 。
不同的三元组是 [-1,0,1] 和 [-1,-1,2] 。
注意,输出的顺序和三元组的顺序并不重要。

示例 2:

输入:nums = [0,1,1]
输出:[]
解释:唯一可能的三元组和不为 0 。

示例 3:

输入:nums = [0,0,0]
输出:[[0,0,0]]
解释:唯一可能的三元组和为 0 。

提示:

  • 3 <= nums.length <= 3000
  • -105 <= nums[i] <= 105

Solution

Language: JavaScript

/**
 * @param {number[]} nums
 * @return {number[][]}
 */

var threeSum = function(nums) {
    let ans = []
    const len = nums.length
    if (nums === null || len < 3) return ans
    nums.sort((a, b) => a - b)

    for (let i = 0; i < nums.length; i++) {
        if (nums[0] > 0) break
        if (i > 0 && nums[i] === nums[i - 1]) continue
        let l = i + 1
        let r = len - 1
        while (l < r) {
            const sum = nums[i] + nums[l] + nums[r]
            if (sum === 0) {
                ans.push([nums[i], nums[l], nums[r]])
                while(l < r && nums[l] === nums[l+1]) l++
                while(l < r && nums[r] === nums[r-1]) r--
                l++
                r--
            }
            else if (sum < 0) l++
            else if (sum > 0) r--
        }
    }

    return ans
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

No branches or pull requests

1 participant