E. Choose and divide
Time Limit: 3000ms
Memory Limit: 131072KB
64-bit integer IO format:
%lld Java class name:
Main
Problem D: Choose and divide
The binomial coefficient C(m,n) is defined asm! C(m,n) = -------- n!(m-n)!
The Input
Input consists of a sequence of lines. Each line contains four non-negative integer numbers giving values for p, q, r, and s, respectively, separated by a single space. All the numbers will be smaller than 10,000 with p>=q and r>=s.The Output
For each line of input, print a single line containing a real number with 5 digits of precision in the fraction, giving the number as described above. You may assume the result is not greater than 100,000,000.Sample Input
10 5 14 9 93 45 84 59 145 95 143 92 995 487 996 488 2000 1000 1999 999 9998 4999 9996 4998
Output for Sample Input
0.12587 505606.46055 1.28223 0.48996 2.00000 3.99960
不得不说,这题极度脑残了。
明明长度是 min(p-q, q),我偏偏写成 min(p-q+1, q);
结果死的不能再死。。。
中途改用一大堆方法,都没搞定;
以为是精度问题。。。(题目就有说明了...)
还自己给自己出了一组超坑爹的数据。o(╯□╰)o
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <time.h>
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <iterator>
using namespace std;
typedef long long LL;
const int MOD = 1e9 + 10;
const int MAXN = 1e6 + 10;
int n, m;
int p, q, r, s;
int main(){
while( EOF != scanf("%d%d%d%d", &p, &q, &r, &s) ){
int lenq = min(p-q, q);
int lenr = min(r-s, s);
int len = max(lenq, lenr);
double ans = 1.0;
for(int i=0; i<len; i++){
if( i<lenq ) ans = ans*(p-i)/(i+1);
if( i<lenr ) ans = ans/(r-i)*(i+1);
}
printf("%.5lf\n", ans);
}
return 0;
}