1221. Split a String in Balanced Strings 分割平衡字符串

• 作者： 负雪明烛
• id： fuxuemingzhu
• 个人博客：https://fuxuemingzhu.cn/

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题目地址：https://leetcode.com/problems/split-a-string-in-balanced-strings/

题目描述

Balanced strings are those who have equal quantity of 'L' and 'R' characters.

Given a balanced string s split it in the maximum amount of balanced strings.

Return the maximum amount of splitted balanced strings.

Example 1:

Input: s = "RLRRLLRLRL"
Output: 4
Explanation: s can be split into "RL", "RRLL", "RL", "RL", each substring contains same number of 'L' and 'R'.

Example 2:

Input: s = "RLLLLRRRLR"
Output: 3
Explanation: s can be split into "RL", "LLLRRR", "LR", each substring contains same number of 'L' and 'R'.

Example 3:

Input: s = "LLLLRRRR"
Output: 1
Explanation: s can be split into "LLLLRRRR".

Constraints:

1. 1 <= s.length <= 1000
2. s[i] = 'L' or 'R'

题目大意

计算一个字符串中有多少个合法的括号匹配。

解题方法

统计

括号匹配可以使用一个变量cnt进行统计，如果遇到左括号，cnt++；如果遇到右括号，cnt—；如果cnt==0说明是一个合法的括号匹配。

C++代码如下：

class Solution {
public:
    int balancedStringSplit(string s) {
        int cnt = 0;
        int res = 0;
        for (char c : s) {
            if (c == 'R') {
                cnt ++;
            } else {
                cnt --;
            }
            if (cnt == 0)
                res ++;
        }
        return res;
    }
};

日期

2019 年 10 月 13 日 —— 国庆调休，这周末只有这一天假