Unique Paths [LeetCode]

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?

Above is a 3 x 7 grid. How many possible unique paths are there?

Note: m and n will be at most 100.

Solution: Pretty easy, use dynamic programming, from bottom line to top line, caculate every the path num of every cell.

 class Solution {
 public:
     int uniquePaths(int m, int n) {
         if(m <=  || n <= )
             return ;
         vector<int> nums;
         for(int i = ; i < m; i ++) {
             if(i == ) {
                 for(int j = ; j < n; j++)
                     nums.push_back();
             } else {
                 for(int j = ; j < n; j ++) {
                     nums[j] += nums[j - ];
                 }
             }
         }
         return nums[n - ];
     }
 };