A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).

The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).

How many possible unique paths are there?

解析：(动态规划)

状态转换方程：d[i][j]=d[i-1][j]+d[i][j-1]

public class Solution {
    public int uniquePaths(int m, int n) {
        if(m==0||n==0)
        return 0;
        if(m==1||n==1)
        return 1;
        int[][] dp=new int[m+1][n+1];
        for(int i=0;i<m+1;i++)
        {
            for(int j=0;j<n+1;j++)
            {
                if(i==1&&j!=0)
                dp[i][j]=1;
                else if(i!=0&&j==1)
                dp[i][j]=1;
          
            }
        }
        for(int i=2;i<=m;i++)
        {
            for(int j=2;j<=n;j++)
            {
            dp[i][j]=dp[i-1][j]+dp[i][j-1];
            }
        }
        return dp[m][n];
    }
}