3963. Create Grid With Exactly One Path

You are given two integers m and n, representing the number of rows and columns of a grid.

Construct any m x n grid consisting only of the characters '.' and '#', where:

• '.' represents a free cell.
• '#' represents an obstacle cell.

A valid path is a sequence of free cells that:

• Starts at the top-left cell (0, 0).
• Ends at the bottom-right cell (m - 1, n - 1).
• Moves only:
  • Right, from (i, j) to (i, j + 1), or
  • Down, from (i, j) to (i + 1, j).

Return any grid such that there is exactly one valid path from the top-left cell to the bottom-right cell.

class Solution {
public:
    vector<string> createGrid(int n, int m) {
        vector<string> res(n, string(m,'#'));
        for(int i = 0; i < n; i++) res[i][0] = '.';
        for(int i = 0; i < m; i++) res[n-1][i] = '.';
        return res;
    }
};