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代码:
#include<stdio.h> int p,q,r,s,i; double ans; int main() { while(~scanf("%d%d%d%d",&p,&q,&r,&s)){ ans=1.0; if(p-q<q) q=p-q; if(r-s<s) s=r-s; for(i=1;i<=q||i<=s;i++){ if(i<=q){ ans=ans*(p-q+i)/i; } if(i<=s){ ans=ans/(r-s+i)*i; } } printf("%.5lf\n",ans); } return 0; }
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原文地址:http://blog.csdn.net/a197p/article/details/45509055