Question 63 of 75 - LeetCode Weekly Challenge

LeetCode Challenge #62. Unique Paths

There is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner (i.e., grid[m - 1][n - 1]). The robot can only move either down or right at any point in time.

Given the two integers m and n, return the number of possible unique paths that the robot can take to reach the bottom-right corner.

The test cases are generated so that the answer will be less than or equal to 2 * 109.

 

Example 1:

robot maze

Input: m = 3, n = 7
Output: 28

Example 2:

Input: m = 3, n = 2
Output: 3
Explanation: From the top-left corner, there are a total of 3 ways to reach the bottom-right corner:
1. Right -> Down -> Down
2. Down -> Down -> Right
3. Down -> Right -> Down

 

Constraints:

  • 1 <= m, n <= 100
Video Solution
C++ Solution
				
					class Solution {
public:
    int mazepath(int i, int j, int n, int m,vector<vector<int>> &dp)
    {
        if(i==n-1 and j==m-1)return 1;
        if(i>=n || j>=m)return 0;
        if(dp[i][j]!=-1)return dp[i][j];
        return dp[i][j]=mazepath(i,j+1,n,m,dp)+mazepath(i+1,j,n,m,dp);
    }
    int uniquePaths(int m, int n) {
        vector<vector<int>> dp(m,vector<int>(n,-1));
        return mazepath(0,0,m,n,dp);
    }
};
				
			

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