LeetCode-in-Rust

15. 3Sum

Medium

Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0.

Notice that the solution set must not contain duplicate triplets.

Example 1:

Input: nums = [-1,0,1,2,-1,-4]

Output: [[-1,-1,2],[-1,0,1]]

Example 2:

Input: nums = []

Output: []

Example 3:

Input: nums = [0]

Output: []

Constraints:

Solution

impl Solution {
    pub fn three_sum(nums: Vec<i32>) -> Vec<Vec<i32>> {
        let mut nums = nums.clone();
        nums.sort();
        let len = nums.len();
        let mut result = Vec::new();

        for i in 0..len - 2 {
            if i > 0 && nums[i] == nums[i - 1] {
                continue;
            }

            let mut l = i + 1;
            let mut r = len - 1;

            while l < r {
                let sum = nums[i] + nums[l] + nums[r];

                if sum < 0 {
                    l += 1;
                } else if sum > 0 {
                    r -= 1;
                } else {
                    result.push(vec![nums[i], nums[l], nums[r]]);

                    while l < r && nums[l] == nums[l + 1] {
                        l += 1;
                    }

                    while l < r && nums[r] == nums[r - 1] {
                        r -= 1;
                    }

                    l += 1;
                    r -= 1;
                }
            }
        }

        result
    }
}