README.md

926. Flip String to Monotone Increasing

A binary string is monotone increasing if it consists of some number of 0's (possibly none), followed by some number of 1's (also possibly none).

You are given a binary string s. You can flip s[i] changing it from 0 to 1 or from 1 to 0.

Return the minimum number of flips to make s monotone increasing.

Example 1:

Input: s = "00110"
Output: 1
Explanation: We flip the last digit to get 00111.

Example 2:

Input: s = "010110"
Output: 2
Explanation: We flip to get 011111, or alternatively 000111.

Example 3:

Input: s = "00011000"
Output: 2
Explanation: We flip to get 00000000.

Constraints:

• 1 <= s.length <= 105
• s[i] is either '0' or '1'.

Solutions (Rust)

1. Solution

impl Solution {
    pub fn min_flips_mono_incr(s: String) -> i32 {
        let s = s.as_bytes();
        let mut count = s.iter().filter(|&&c| c == b'0').count() as i32;
        let mut ret = count;

        for i in 0..s.len() {
            count += (s[i] == b'1') as i32 - (s[i] == b'0') as i32;

            ret = ret.min(count);
        }

        ret
    }
}