16. 3Sum Closest
Given an array nums
of n integers and an integer target
, find three integers 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.
Example 1:
Input: nums = [-1,2,1,-4], target = 1 Output: 2 Explanation: The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
Constraints:
3 <= nums.length <= 10^3
-10^3 <= nums[i] <= 10^3
-10^4 <= target <= 10^4
Rust Solution
struct Solution;
use std::i32;
impl Solution {
fn three_sum_closest(mut nums: Vec<i32>, target: i32) -> i32 {
nums.sort_unstable();
let n = nums.len();
let mut res = 0;
let mut diff = i32::MAX;
for i in 0..n - 2 {
let mut l = i + 1;
let mut r = n - 1;
while l < r {
let sum = nums[l] + nums[r] + nums[i];
if sum == target {
return target;
}
if (sum - target).abs() < diff {
diff = (sum - target).abs();
res = sum;
}
if nums[l] + nums[r] > target - nums[i] {
r -= 1;
} else {
l += 1;
}
}
}
res
}
}
#[test]
fn test() {
let nums = vec![-1, 2, 1, -4];
let target = 1;
let res = 2;
assert_eq!(Solution::three_sum_closest(nums, target), res);
}
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