HDU 2131 Probability

http://acm.hdu.edu.cn/showproblem.php?pid=2131

Problem Description

Mickey is interested in probability recently. One day , he played a game which is about probability with mini.First mickey gives a letter and a word to mini.Then mini calculate the probability that the letter appears in the word.For example,give you the letter "a" and the word "apple". the probability of this case is 0.20000.

 

Input

The input contains several test cases. Each test case consists of a letter and a word.The length of the word is no longer than 200.

 

Output

For each test case, print the probability rounded to five digits after the decimal point.

 

Sample Input

a apple

c Candy

a banana

 

Sample Output

0.20000

0.20000

0.50000

 

代码：

#include <bits/stdc++.h>
using namespace std;

const int maxn = 1e5 + 10;
char s[maxn];
char c;

int main() {
    while(~scanf("%c%s", &c, s)) {
        getchar();
        int len = strlen(s);
        int cnt = 0;
        for(int i = 0; i< len; i ++) {
            if(s[i] == c || s[i] == c - 32 || s[i] == c + 32)
                cnt ++;
        }
        printf("%.5lf\n", 1.0 * cnt / len);
    }
    return 0;
}