题解 | 最长的括号匹配用栈记录左括号位置然后依次匹配就行

#include<stdio.h>
#include<string.h>

int main() {
    char s[30000];
    scanf("%s", &s);
    int n = strlen(s);
    int stack[n], top = -1, ans = 0;
    for (int i = 0; i < n; i++) stack[i] = 0;
    stack[++top] = -1;
    for (int i = 0; i < n; i++) {
        if (s[i] == '(') stack[++top] = i;
        else {
            --top;
            if (top == -1) stack[++top] = i;
            else if (i - stack[top] > ans) ans = i - stack[top];
        }
    }
    printf("%d\n", ans);
    return 0;
}