Longest Valid Parentheses

最新推荐文章于 2022-09-01 00:56:47 发布

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本文介绍了一种求解字符串中最长有效括号子串长度的方法。通过遍历字符串并利用辅助数组记录有效括号的位置及长度，最终找出最长的有效括号子串长度。

Longest Valid Parentheses

Given a string containing just the characters `'('` and `')'`, find the length of the longest valid (well-formed) parentheses substring.

For `"(()"`, the longest valid parentheses substring is `"()"`, which has length = 2.

Another example is `")()())"`, where the longest valid parentheses substring is `"()()"`, which has length = 4.

Java代码：

public class Solution {
    public int longestValidParentheses(String s) {
        char[] S = s.toCharArray();
		int[] V = new int[S.length];
		int open = 0;
		int max = 0;
		for (int i = 0; i < S.length; i++) {
			if (S[i] == '(')
				open++;
			if (S[i] == ')' && open > 0) {
				V[i] = 2 + V[i - 1];
				if(i-V[i] >= 0) {
                    V[i] += V[i-V[i]];  //处理“（）（）”这种情况
				}
				open--;
			}
			if (V[i] > max)
				max = V[i];
		}
		return max;
    }
}