HackerRank "Bot Saves Princess" beginner code

I submitted the following Python 3 code for this HackerRank challenge. Given an n × n grid with an m in the center and a p in one corner, it prints the directions to move the m to the p.

I wanted to know how improve it or other observations.

#!/usr/bin/python
def displayPathtoPrincess(n,grid):
    #first, find where p is located 
    flag = True
    n = n-1
    while(flag):
        if grid[0][n] == 'p':
            flag = False 
            a = 0
            b = n
        if grid[n][0] == 'p':
            flag = False 
            a = n
            b = 0
        if grid[0][0] == 'p':
            flag = False 
            a = 0
            b = 0 
        if grid[n][n] == 'p':
            flag = False 
            a = n
            b = n 
        #else:
            #print("Something broke?") #Why does this execute?
        y = a - int(n/2)
        x = b - int(n/2)    
        while 0 != y:
            if y  0:
                y = y-1
                print("DOWN")
        while 0 != x:
            if x 0:
                x = x-1
                print("RIGHT")

m = int(input())
grid = [] 
for i in range(0, m): 
    grid.append(input().strip())

displayPathtoPrincess(m,grid)

The function should be path_to_princess(grid), using the naming convention specified in PEP 8. The n parameter is redundant, as it can be inferred from the grid's dimensions. In any case, redefining n=n-1 is confusing. Also, it would be better to leave all I/O out of the function, so that it just does computation.

The while(flag) loop shouldn't exist. If the princess is in another castle, you'll end up with an infinite loop; otherwise, the code executes just once.

Use the // operator for integer division.

Explicit looping can be greatly reduced through liberal use of list comprehensions, generators, and list multiplication.

def path_to_princess(grid):
    z = len(grid) - 1
    corners = [
        (0, 0), (0, z),
        (z, 0), (z, z)
    ]
    p = next((r, c) for r, c in corners if grid[r][c] == 'p')
    m = (z // 2, z // 2)
    row_diff, col_diff = p[0] - m[0], p[1] - m[1]    
    yield from (['UP'] * -row_diff if row_diff < 0 else ['DOWN'] * row_diff)
    yield from (['LEFT'] * -col_diff if col_diff < 0 else ['RIGHT'] * col_diff)

n = int(input())
grid = [input().strip() for _ in range(n)]
for move in path_to_princess(grid):
    print(move)

StackExchange Code Review Q#131592, answer score: 8