Problem:
The goal of 8 Queens Problem is to put eight queens on a chess-board such that none of them threatens any of others. A queen threatens the squares in the same row, in the same column, or on the same diagonals as shown in the following figure.      For a given chess board where $k$ queens are already placed, find the solution of the 8 queens problem.

Incorrect submission (verdict: Wrong Answer):
import copy

n = int(input())

dotsa = []
for _ in range(n):
    y,x = map(int,input().split(" "))
    dotsa.append([y,x])

pattern = []
pattern.append(dotsa)


for y in range(8):
    nextpattern = []
    #print("#######")
    #print(pattern)
    for pat in pattern:
        #print(";;;;;;;;;;;;;;;;;;;;;")
        #print(pat)
        flag = False
        for dot in pat:
            if dot[0] == y:
                flag = True
                break

        if flag:
            nextpattern = pattern
            continue

        ifFound = False
        for x in range(8):
            ank = len(pat)
            flag2 = True
            for i in range(ank):
                if abs(pat[i][0]-y) == abs(pat[i][1]-x) or pat[i][1] == x:
                    flag2 = False
                    break
            if flag2:
                #print("appended")
                #print(y)
                #print(x)
                tmp = copy.deepcopy(pat)
                tmp.append([y,x])
                nextpattern.append(tmp)
        
    pattern = nextpattern

ans = pattern[0]
board = [["."]*8 for i in range(8)]
#print(ans)
for ele in ans:
    board[ele[1]][ele[0]] = "Q"
for row in board:
    print(''.join(map(str,row)))



Fixed, accepted submission:
import itertools


def hand_in_answer(v):
    base = [".", ".", ".", ".", ".", ".", ".", "."]
    for i in range(8):
        tmp = base.copy()
        tmp[v[i]] = "Q"
        print("".join(tmp))


def ifGoodPosition(position, v):
    yo = position[0]
    xo = position[1]

    x = xo
    y = yo
    x += 1
    y += 1
    while x < 8 and x >= 0 and y >= 0 and y < 8:
        if v[y] == x:
            return False
        x += 1
        y += 1

    x = xo
    y = yo
    x += 1
    y -= 1
    while x < 8 and x >= 0 and y >= 0 and y < 8:
        if v[y] == x:
            return False
        x += 1
        y -= 1

    x = xo
    y = yo
    x -= 1
    y += 1
    while x < 8 and x >= 0 and y >= 0 and y < 8:
        if v[y] == x:
            return False
        x -= 1
        y += 1

    x = xo
    y = yo
    x -= 1
    y -= 1
    while x < 8 and x >= 0 and y >= 0 and y < 8:
        if v[y] == x:
            return False
        x -= 1
        y -= 1

    return True


fixed_q_count = int(input())
x_choices = set([_ for _ in range(8)])
fixed_qs = []
for _ in range(fixed_q_count):
    y, x = map(int, input().split(" "))
    fixed_qs.append([y, x])

for v in itertools.permutations(x_choices, 8):
    flag2 = True
    for fixed_q in fixed_qs:
        if not v[fixed_q[0]] == fixed_q[1]:
            flag2 = False
            break

    if not flag2:
        continue

    flag = True
    for y in range(8):
        if not ifGoodPosition([y, v[y]], v):
            flag = False
            break

    if flag:
        hand_in_answer(v)
        break