排列组合问题

#include<iostream>#include<set>#include<cstdlib>#include<ctime>#include<vector>#include<string>#include<algorithm>#include<cstdio>#include<sstream>#include<algorithm>#include<map>using namespace std;int f(int m,int n){    if(m==0||n==0) return 1;    return f(m-1,n)+f(m,n-1);}int main(){    cout<<f(2,2)<<endl;    return 0;}