---
title: 1529. Minimum Suffix Flips
tags: String
description: share source code.
---

# 1529. Minimum Suffix Flips

class Solution {
    public int minFlips(String target) {
        char start [] = new char [target.length()];
        Arrays.fill(start, '0');
        // 重第一個開始翻
        return helper(new String(start), target, 0, 0);
    }
    
    public int helper(String start, String target, int idx, int cnt){
        
        if(idx >= start.length()){
            return 0;
        }
        
        // 如果翻的次數是奇數才在改變數字
        char ch = start.charAt(idx);
        if(cnt % 2 == 1){
            ch = ch == '0' ? '1' :'0';
        }
        
        int ret = 0;
        if( ch != target.charAt(idx)){
            ret += helper(start, target, idx + 1,  cnt + 1) + 1;
        }else{
            ret += helper(start, target, idx + 1,  cnt);
        }
        
        return ret;
    }
}