[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。

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

using namespace std;

const int maxn = 100010;
const int INF = (1<<18);

char str[maxn];
int pos[maxn];

int main() {
    // freopen("in", "r", stdin);
    int T;
    int kase = 1;
    scanf("%d", &T);
    while(T--) {
        memset(pos, 0, sizeof(pos));
        scanf("%s", str);
        int len = strlen(str);
        int cnt = 0;    //how c
        int flag = 0;   //not
        for(int i = 0; str[i]; i++) {
            if(str[i] != 'c' && str[i] != 'f') {
                flag = 1;
                break;
            }
            if(str[i] == 'c') {
                cnt++;
            }
        }
        if(flag) {
            printf("Case #%d: -1
", kase++);
            continue;
        }
        if(cnt == 0) {
            printf("Case #%d: %d
",kase++, len / 2 + len % 2);
            continue;
        }
        int fir = INF;
        int cur = 0;
        for(int i = 0; str[i]; i++) {
            if(str[i] == 'c') {
                if(fir == INF) {
                    fir = i;
                }
                pos[cur++] = i;
            }
        }
        pos[cur++] = fir + len;   //circle
        for(int i = 1; i < cur; i++) {
            if(pos[i] - pos[i-1] <= 2) {
                flag = 1;
                break;
            }
        }
        if(flag) {
            printf("Case #%d: -1
", kase++);
        }
        else {
            printf("Case #%d: %d
", kase++, cnt);
        }
    }
}