Distance of nearest cell having 1 (GFG)

class Solution 
{
    public:
    class Point {
        public:
        int x, y;
        Point(int _x, int _y) {
            x = _x;
            y = _y;
        }
    };
    
    //Function to find distance of nearest 1 in the grid for each cell.
	vector<vector<int>>nearest(vector<vector<int>>grid)
	{
	    // Code here
	    queue<Point> Queue;
	    int n = grid.size();
	    int m = grid[0].size();
	    for(int i = 0; i < n; i++) {
	        for(int j = 0; j < m; j++) {
	            if(grid[i][j] == 1) {
	                Queue.push(Point(i, j));
	            }
	            grid[i][j] = -1;
	        }
	    }
	    int ans = -1;
	    while(!Queue.empty()) {
	        int sz = Queue.size();
	        ans++;
	        for(int k = 0; k < sz; k++) {
	            Point temp = Queue.front();
	            Queue.pop();
	            int i = temp.x;
	            int j = temp.y;
	            if(grid[i][j] == -1) {
	                if(i - 1 >= 0 && i - 1 < n && j >= 0 && j < m && grid[i - 1][j] == -1)
	                Queue.push(Point(i - 1, j));
	                if(i + 1 >= 0 && i + 1 < n && j >= 0 && j < m && grid[i + 1][j] == -1)
	                Queue.push(Point(i + 1, j));
	                if(i >= 0 && i < n && j - 1 >= 0 && j - 1 < m && grid[i][j - 1] == -1)
	                Queue.push(Point(i, j - 1));
	                if(i >= 0 && i < n && j + 1 >= 0 && j + 1 < m && grid[i][j + 1] == -1)
	                Queue.push(Point(i, j + 1));
	                grid[i][j] = ans;
	            }
	        }
	    }
	    return grid;
	}
};