CodeForces - 1023C

AC代碼：

#include <algorithm>
#include <cstdio>
#include <iostream>
#include <cstring>

using namespace std;

char a[200010], b[200010];
int main()
{
    int n, m;
    scanf("%d%d", &n, &m);
    scanf("%s", a);
    memset(b, 0, sizeof(b));
    int j = 0, x = 0;
    for (int i = 0; i < strlen(a); i++) {	//記錄"("數量
        if (a[i] == '(') {
            b[j++] = '(';
            x++;
        }
        if (a[i] == ')') {
            b[j++] = ')';
        }
        if (x == m / 2)
            break;
    }
    for (int i = j; i < m; i++)			//補全")"
        b[i] = ')';
    cout << b;
    return 0;
}