Minimum operations to make array equal to target

Array Dynamic Programming Stack Greedy Monotonic Stack

41.3% acceptance

Feb 25, 2026

293

You are given two positive integer arrays nums and target, of the same length. In a single operation, you can select any subarray of nums and increment each element within that subarray by 1 or decrement each element within that subarray by 1. Return the minimum number of operations required to make nums equal to the array target.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn minimum_operations(nums: Vec<i32>, target: Vec<i32>) -> i64 {
    let n = nums.len();
    let mut ans = 0i64;
    let mut prev_pos = 0i64; // previous positive diff
    let mut prev_neg = 0i64; // previous negative diff (stored as positive)
    for i in 0..n {
      let d = target[i] as i64 - nums[i] as i64;
      let pos = d.max(0);
      let neg = (-d).max(0);
      // Rising slope of positive part
      ans += (pos - prev_pos).max(0);
      // Rising slope of negative part
      ans += (neg - prev_neg).max(0);
      prev_pos = pos;
      prev_neg = neg;
    }
    ans
  }
}