Minimum operations to make binary array elements equal to one i

Array Bit Manipulation Queue Sliding Window Prefix Sum

80.4% acceptance

Feb 24, 2026

673

You are given a binary array nums. You can do the following operation on the array any number of times (possibly zero): Choose any 3 consecutive elements from the array and flip all of them. Flipping an element means changing its value from 0 to 1, and from 1 to 0. Return the minimum number of operations required to make all elements in nums equal to 1. If it is impossible, return -1.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn min_operations(nums: Vec<i32>) -> i32 {
    let n = nums.len();
    let mut nums = nums;
    let mut ops = 0;
    for i in 0..n - 2 {
      if nums[i] == 0 {
        nums[i] ^= 1;
        nums[i + 1] ^= 1;
        nums[i + 2] ^= 1;
        ops += 1;
      }
    }
    if nums[n - 2] == 1 && nums[n - 1] == 1 {
      ops
    } else {
      -1
    }
  }
}