贪心+stack Codeforces Beta Round #5 C. Longest Regular Bracket Sequence

 /*
题意：求最长括号匹配的长度和它的个数
贪心+stack：用栈存放最近的左括号的位置，若是有右括号匹配，则记录它们的长度，更新最大值，可以在O (n)解决
详细解释：http://blog.csdn.net/taoxin52/article/details/26012167
*/
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <stack>
using namespace std;

const int MAXN = 1e6 + 10;
const int INF = 0x3f3f3f3f;
char s[MAXN];
int len[MAXN];
stack<int> S;

int main(void)        //Codeforces Beta Round #5 C. Longest Regular Bracket Sequence
{
//    freopen ("C.in", "r", stdin);

while (scanf ("%s", s) == 1)
{
while (!S.empty ())    S.pop ();
memset (len, 0, sizeof (len));

int mx = 0;    int cnt = 0;
for (int i=0; s[i]; ++i)
{
if (s[i] == '(')    S.push (i);
else
{
if (!S.empty ())
{
int p = S.top ();    S.pop ();
len[i] = (p > 0 ? len[p-1] : 0) + (i - p + 1);
}
}
if (len[i] > mx)    {mx = len[i];    cnt = 1;}
else if (len[i] == mx)    {cnt++;}
}

if (mx == 0)    puts ("0 1");
else    printf ("%d %d\n", mx, cnt);
}

return 0;
}