HDU 1570 A C

A C

Problem Description

Are you excited when you see the title "AC" ? If the answer is YES , AC it ;

You must learn these two combination formulas in the school . If you have forgotten it , see the picture.




Now I will give you n and m , and your task is to calculate the answer .

 

Input

In the first line , there is a integer T indicates the number of test cases.
Then T cases follows in the T lines.
Each case contains a character 'A' or 'C', two integers represent n and m. (1<=n,m<=10)

 

Output

For each case , if the character is 'A' , calculate A(m,n),and if the character is 'C' , calculate C(m,n).
And print the answer in a single line.

 

Sample Input

2A 10 10C 4 2

 

Sample Output

36288006

题意：照公式计算。

for循环，n-m到n。

#include<stdio.h>#include<string.h>int main(){    int m,n,t,i;    char c;    __int64 sum;    scanf("%d",&t);    while(t--)    {        scanf("%c",&c);        if(c!='A'&&c!='C')        {            t++;            continue;        }        scanf("%d%d",&n,&m);        sum=1;        if(c=='A')        {            for(i=n-m+1; i<=n; i++)            {                sum*=i;            }        }        else if(c=='C')        {            for(i=n-m+1; i<=n; i++)            {                sum*=i;            }            for(i=1;i<=m;i++)            {                sum/=i;            }        }        printf("%I64d\n",sum);    }    return 0;}