题解 | 二维斐波那契数列

#include <iostream>
using namespace std;
#include <vector>
#include <cmath>
const int mod=1e9+7;
int main() {
    int n,m;
    cin>>n>>m;
      vector<vector<long long>>s(n+1,vector<long long>(m+1,0));
      for(int i=1;i<n+1;i++){
        for(int j=1;j<m+1;j++){
            if(i==1&&j==1)s[i][j]=1;
            else if(i>=2&&j==1)s[i][j]=s[i-1][j]%mod;
            else if(i==1&&j>=2)s[i][j]=s[i][j-1]%mod;
            else if(i>=2&&j>=2)s[i][j]=s[i-1][j]+s[i][j-1]%mod;
        }
      }
      cout<<s[n][m]%mod<<endl;
      return 0;
}