Leetcode 62. Unique Paths (Medium) (cpp)

/*

62. Unique Paths (Medium)

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?

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