3sum closest

Array Two Pointers Sorting

48.1% acceptance

Jan 12, 2026

11563

618

Given an integer array nums of length n and an integer target, find three integers at distinct indices in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

Solution

Rust

Time O(n²)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn three_sum_closest(nums: Vec<i32>, target: i32) -> i32 {
    let mut nums = nums;
    nums.sort();
    let n = nums.len();
    let mut closest_sum = nums[0] + nums[1] + nums[2];
    
    for i in 0..n-2 {
      let mut left = i + 1;
      let mut right = n - 1;
      
      while left < right {
        let sum = nums[i] + nums[left] + nums[right];
        
        if (sum - target).abs() < (closest_sum - target).abs() {
          closest_sum = sum;
        }
        
        if sum < target {
          left += 1;
        } else if sum > target {
          right -= 1;
        } else {
          return sum;
        }
      }
    }
    
    closest_sum
  }
}