题解 | 小红走矩阵

#include <bits/stdc++.h>
using namespace std;
using ll = long long int;
using ld = long double;
using PII=pair<ll,ll>;
using PIII=pair<int,pair<int,int>>;
const ld ESP = 1e-10;
const ld PI = acosl(-1);
const int N=1e5+10;
const int M=2e5+10;
// const int mod = 1000000007;
const int mod = 998244353;
//随机化
random_device rd;
mt19937 gen(rd());
uniform_int_distribution<> dis(1, 1000000000);
// cout<<fixed<<setprecision(10);

void solve(){
    int n,m;
    cin>>n>>m;
    ll dp[1010][1010]={};
    dp[1][1]=1;
    for(int j=1;j<=m;j++){
        for(int i=1;i<=n;i++){
            if(i==1&&j==1)continue;
            dp[i][j]=(dp[i-1][j]+dp[i][j-1])%mod;
        }
    }
    cout<<dp[n][m];
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int _=1;
    // cin>>_;
    while(_--){
        solve();
    }
    return 0;
}