class Solution {
public:
    int uniquePaths(int m, int n) {
        if(m <= 1 || n<=1) return 1;
        vector<vector<int>> dp( m+1 , vector<int>(n+1,0));
        dp[1][1] = 1;
        dp[1][2] = 1;
        dp[2][1] = 1;
        for(int i=1 ; i<=m ; i++)
        {
            for(int j=1 ; j<=n ; j++)
            {   
                if(dp[i][j] != 0 ) continue;
                dp[i][j] = dp[i-1][j] + dp[i][j-1];
                // cout<<"i:"<<i<<" j:"<<j<<"   dp:"<<dp[i][j]<<endl;
            }
        }
        return dp[m][n];
    }
};

class Solution {
public:
    int uniquePaths(int m, int n) {
        vector<vector<int>> dp(m,vector<int>(n,0));
        for(int i=0 ; i<n ;i++)
            dp[0][i] = 1;
        for(int i=0 ; i<m ;i++)
            dp[i][0] = 1;
        for(int i = 1 ; i<m ; i++)
        {
            for(int j = 1 ; j<n ; j++)
            {
                dp[i][j] = dp[i-1][j] + dp[i][j-1]; 
            }
        }
        return dp[m-1][n-1];
    }
};