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.

class Solution {
    int dp[101][101]{0,};
public:
    int uniquePaths(int m, int n) {
        for(int i = 0; i < m; i++) dp[i][0] = 1;
        for(int j = 0; j < n; j++) dp[0][j] = 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];
    }
};