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 }