Merge operations to turn array into a palindrome

Array Two Pointers Greedy

68.9% acceptance

Mar 31, 2026

153

You are given an array nums consisting of positive integers. You can perform the following operation on the array any number of times: Choose any two adjacent elements and replace them with their sum. For example, if nums = [1,2,3,1], you can apply one operation to make it [1,5,1]. Return the minimum number of operations needed to turn the array into a palindrome.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn minimum_operations(nums: Vec<i32>) -> i32 {
    let mut left = 0usize;
    let mut right = nums.len() - 1;
    let mut l_sum = nums[left] as i64;
    let mut r_sum = nums[right] as i64;
    let mut ops = 0;
    while left < right {
      if l_sum == r_sum {
        left += 1;
        right -= 1;
        if left < right {
          l_sum = nums[left] as i64;
          r_sum = nums[right] as i64;
        }
      } else if l_sum < r_sum {
        left += 1;
        l_sum += nums[left] as i64;
        ops += 1;
      } else {
        right -= 1;
        r_sum += nums[right] as i64;
        ops += 1;
      }
    }
    ops
  }
}