leetcode[62]Unique Paths

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.

class Solution {
public:
int uniquePaths(int m, int n) 
{
    vector<int> ivec(n);
    vector<vector<int>> f(m, ivec);
    for (int ki=0;ki<m;ki++)
    {
        f[ki][0]=1;
    }
    for (int kj=0;kj<n;kj++)
    {
        f[0][kj]=1;
    }
    for (int i=1;i<m;i++)
    {
        for (int j=1;j<n;j++)
        {
            f[i][j]=f[i-1][j]+f[i][j-1];
        }
    }
    return f[m-1][n-1];
}
};