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Strange multidimensional list element changing

I'm trying to make a solution for the n queens problem and I want to make a code writing a number of possible solutions for a n X n board and n queens.

Here is my code:

n = int(input())
piony = [[False for i in range(n)] for j in range(n)]
skosy_lp = [[False for i in range(n)] for j in range(n)]
skosy_pl = [[False for i in range(n)] for j in range(n)]
figury = [-1] * n
counter = 0
layer = 0
#list creating etc. piony list is containing vertical lines occupied by queens, skosy_lp
#is containing lines oblique from left to right, skosy_pl - from right to left.
#this is a backtracking algorithm
#figury list is containing positions of queens. -1 means that the queen isn't placed
while True:
    if layer == -1:
        break
    piony[layer] = piony[layer-1]
    skosy_pl[layer] = skosy_pl[layer-1]
    skosy_pl[layer].append(False)
    skosy_pl[layer].pop(0)
    skosy_lp[layer] = skosy_lp[layer-1]
    skosy_lp[layer].insert(0, False)
    skosy_lp[layer].pop(n)
    figury[layer]+=1
    while figury[layer] < n and (piony[layer][figury[layer]] or skosy_lp[layer][figury[layer]]or skosy_lp[layer][figury[layer]]):
        figury[layer] +=1
    if figury[layer] == n:
        figury[layer] = -1
        piony[layer] = [False] * n
        skosy_pl[layer] = [False] * n
        skosy_lp[layer] = [False] * n
        layer-=1
    else:
        if layer == n-1:
            counter+=1
            layer-=1
        else:
            print(piony)
            #I think there is a bug
            piony[layer][figury[layer]] = True
            skosy_pl[layer][figury[layer]] = True
            skosy_lp[layer][figury[layer]] = True
            layer+=1

When I stop a program in the middle, I discover that when I make piony[layer][figury[layer]] = True for layer = 0 (and figury[layer] = 0) the program is changing piony[0][0] and piony[-1][0].

Can someone tell me why and how to fix it?



source https://stackoverflow.com/questions/76292028/strange-multidimensional-list-element-changing
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