[HDOJ5455]Fang Fang

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=5455

先判断一发，然后记下c出现的位置（还要考虑转回到头部的情况），总之有c总会比单个f或者双f更少。

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <algorithm>
 5 #include <cmath>
 6
 7 using namespace std;
 8
 9 const int maxn = 100010;
10 const int INF = (1<<18);
11
12 char str[maxn];
13 int pos[maxn];
14
15 int main() {
16     // freopen("in", "r", stdin);
17     int T;
18     int kase = 1;
19     scanf("%d", &T);
20     while(T--) {
21         memset(pos, 0, sizeof(pos));
22         scanf("%s", str);
23         int len = strlen(str);
24         int cnt = 0;    //how c
25         int flag = 0;   //not
26         for(int i = 0; str[i]; i++) {
27             if(str[i] != ‘c‘ && str[i] != ‘f‘) {
28                 flag = 1;
29                 break;
30             }
31             if(str[i] == ‘c‘) {
32                 cnt++;
33             }
34         }
35         if(flag) {
36             printf("Case #%d: -1\n", kase++);
37             continue;
38         }
39         if(cnt == 0) {
40             printf("Case #%d: %d\n",kase++, len / 2 + len % 2);
41             continue;
42         }
43         int fir = INF;
44         int cur = 0;
45         for(int i = 0; str[i]; i++) {
46             if(str[i] == ‘c‘) {
47                 if(fir == INF) {
48                     fir = i;
49                 }
50                 pos[cur++] = i;
51             }
52         }
53         pos[cur++] = fir + len;   //circle
54         for(int i = 1; i < cur; i++) {
55             if(pos[i] - pos[i-1] <= 2) {
56                 flag = 1;
57                 break;
58             }
59         }
60         if(flag) {
61             printf("Case #%d: -1\n", kase++);
62         }
63         else {
64             printf("Case #%d: %d\n", kase++, cnt);
65         }
66     }
67 }