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

题目传送门

 1 /*
 2     题意：求最长括号匹配的长度和它的个数
 3     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
 4     详细解释：http://blog.csdn.net/taoxin52/article/details/26012167
 5 */
 6 #include <cstdio>
 7 #include <algorithm>
 8 #include <cstring>
 9 #include <cmath>
10 #include <stack>
11 using namespace std;
12
13 const int MAXN = 1e6 + 10;
14 const int INF = 0x3f3f3f3f;
15 char s[MAXN];
16 int len[MAXN];
17 stack<int> S;
18
19 int main(void)        //Codeforces Beta Round #5 C. Longest Regular Bracket Sequence
20 {
21 //    freopen ("C.in", "r", stdin);
22
23     while (scanf ("%s", s) == 1)
24     {
25         while (!S.empty ())    S.pop ();
26         memset (len, 0, sizeof (len));
27
28         int mx = 0;    int cnt = 0;
29         for (int i=0; s[i]; ++i)
30         {
31             if (s[i] == ‘(‘)    S.push (i);
32             else
33             {
34                 if (!S.empty ())
35                 {
36                     int p = S.top ();    S.pop ();
37                     len[i] = (p > 0 ? len[p-1] : 0) + (i - p + 1);
38                 }
39             }
40             if (len[i] > mx)    {mx = len[i];    cnt = 1;}
41             else if (len[i] == mx)    {cnt++;}
42         }
43
44         if (mx == 0)    puts ("0 1");
45         else    printf ("%d %d\n", mx, cnt);
46     }
47
48     return 0;
49 }