动态规划解决

#include<iostream>
#include<vector>
using namespace std;

int main(){
    int a,b;
    while(cin>>a>>b){
        vector<vector<int>>dp(a+1,vector<int>(b+1,0));
        for(int i=0;i<=a;i++)dp[i][0]=1;
        for(int i=0;i<=b;i++)dp[0][i]=1;
        for(int i=1;i<=a;i++){
            for(int j=1;j<=b;j++){
                dp[i][j]=dp[i-1][j]+dp[i][j-1];
                //cout<<dp[i][j]<<" ";
            }
           // cout<<endl;
        }
        cout<<dp[a][b]<<endl;
    }
    return 0;
}