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ac代码:
#include<stdio.h> #include<math.h> #include<string.h> #include<stack> #include<set> #include<queue> #include<vector> #include<iostream> #include<algorithm> #define MAXN 10100000 #define LL long long #define ll __int64 #define INF 0xfffffff #define mem(x) memset(x,0,sizeof(x)) #define PI acos(-1) using namespace std; LL gcd(LL a,LL b){return b?gcd(b,a%b):a;} LL lcm(LL a,LL b){return a/gcd(a,b)*b;} LL powmod(LL a,LL b,LL MOD){LL ans=1;while(b){if(b%2)ans=ans*a%MOD;a=a*a%MOD;b/=2;}return ans;} //head int c[2222][2222]; void db() { for(int i=1;i<=2010;i++) c[i][0]=1,c[i][i]=1; for(int i=2;i<=2010;i++) { c[i][1]=i%1007; for(int j=2;j<=2010;j++) c[i][j]=(c[i-1][j]+c[i-1][j-1])%1007; } } int main() { db(); int t; scanf("%d",&t); while(t--) { int n,m; scanf("%d%d",&m,&n); if(m>n) { printf("0\n"); continue; } printf("%d\n",c[n][m]); } return 0; }