easy递推

#include <bits/stdc++.h>
using namespace std;
int n,m;
int a[1005][1005];
bool vis[1005][1005];
int main(){
cin >> n >> m;
for(int i = 1;i<=m;i++){
int x,y;
cin >> x >> y;
vis[x][y] = 1;
}
a[0][1]=1;//假设从(0,1)位置走到(1,1)
a[0][0]=0;
for(int i = 1;i<=n;i++){
for(int j = 1;j<=n;j++){
if(vis[i][j]==0){
a[i][j] = a[i-1][j]+a[i][j-1];
a[i][j]%=100003;
}
}
}
cout << a[n][n] << endl;
return 0;
}