2380-TimeNeededToRearrangeABinaryString.go

package main

// 2380. Time Needed to Rearrange a Binary String
// You are given a binary string s. 
// In one second, all occurrences of "01" are simultaneously replaced with "10". 
// This process repeats until no occurrences of "01" exist.

// Return the number of seconds needed to complete this process.

// Example 1:
// Input: s = "0110101"
// Output: 4
// Explanation: 
// After one second, s becomes "1011010".
// After another second, s becomes "1101100".
// After the third second, s becomes "1110100".
// After the fourth second, s becomes "1111000".
// No occurrence of "01" exists any longer, and the process needed 4 seconds to complete,
// so we return 4.

// Example 2:
// Input: s = "11100"
// Output: 0
// Explanation:
// No occurrence of "01" exists in s, and the processes needed 0 seconds to complete,
// so we return 0.

// Constraints:
//     1 <= s.length <= 1000
//     s[i] is either '0' or '1'.

// Follow up:
//     Can you solve this problem in O(n) time complexity?

import "fmt"

func secondsToRemoveOccurrences(s string) int {
    res, zero := 0, 0
    max := func (x, y int) int { if x > y { return x; }; return y; }
    for _, v := range s {
        if v == '0' {
            zero++
        } else if zero > 0 {
            res = max(res + 1, zero)
        }
    }
    return res
}

func main() {
    // Example 1:
    // Input: s = "0110101"
    // Output: 4
    // Explanation: 
    // After one second, s becomes "1011010".
    // After another second, s becomes "1101100".
    // After the third second, s becomes "1110100".
    // After the fourth second, s becomes "1111000".
    // No occurrence of "01" exists any longer, and the process needed 4 seconds to complete,
    // so we return 4.
    fmt.Println(secondsToRemoveOccurrences("0110101")) // 4
    // Example 2:
    // Input: s = "11100"
    // Output: 0
    // Explanation:
    // No occurrence of "01" exists in s, and the processes needed 0 seconds to complete,
    // so we return 0.
    fmt.Println(secondsToRemoveOccurrences("11100")) // 0
}