A rook is a piece used in the game of chess which is played on a board of square grids. A rook can only move vertically or horizontally from its current position and two rooks attack each other if one is on the path of the other. In the following figure, the dark squares represent the reachable locations for rook R1 from its current position. The figure also shows that the rook R1 and R2 are in attacking positions where R1 and R3 are not. R2 and R3 are also in non-attacking positions.
Case 8: 0
给你一个N*N的方格,放K个棋子(棋子是不同的,并且不能同行或者同列)问有多少种方法,利用组合数学的知识A(n,k)*c(n,k)即为所求,不过计算时要注意不能直接算,这样long long 也会超。。。。。。。。。。。。
#include<stdio.h> #include<string.h> #include<algorithm> using namespace std; int main() { long long sum1,sum2,num,help; int i,j,t,n,m,k; int flag=1; scanf("%d",&t); while(t--) { sum1=1; sum2=1; scanf("%d%d",&n,&k); printf("Case %d: ",flag++); if(k>n) { printf("0\n"); continue; } else { help=1; for(i=n;i>n-k;i--) help*=i; for(i=1;i<=k;i++) { sum1=sum1*(n-i+1)/i; } printf("%lld\n",sum1*help); } } return 0; }