Unique Paths

<-M 62> Unique Paths

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