If the replacement of elements is written in two lines, then the matrix is transported incorrectly
x=[[i for i in list(map(int,input().split()))]
for _ in range(int(input()))]
print("Result:")
for i in range(len(x)):
for j in range(i,len(x)):
if i>0:
j-=1
x[i][j]=x[j][i]
x[j][i]=x[i][j]
[print(*i) for i in x]
Input: 3 1 2 3 4 5 6 7 8 9
Result: 1 4 7 4 5 6 7 6 9
If the replacement of elements is written in one line, then the transportation of the matrix occurs correctly
x=[[i for i in list(map(int,input().split()))]
for _ in range(int(input()))]
print("Result:")
for i in range(len(x)):
for j in range(i,len(x)):
x[i][j],x[j][i]=x[j][i],x[i][j]
[print(*i) for i in x]
Input: 3 1 2 3 4 5 6 7 8 9
Result: 1 4 7 2 5 8 3 6 9
Why is this happening? I don't understand the difference
Let's simplify this by removing the indices and assigning sample values:
A = x[i][j] = 4
B = x[j][i] = 2
Now do your two lines:
A = B # what is the value of A now? of B?
B = A # what is the value of B now? of A?
A is overwritten with the value of B, then that new value is copied back to B. The original value of A is lost.
When using one line:
A, B = B, A
Python (I assume that's the language you use) creates an intermediate tuple that stores the original values of B and A, then swaps them when writing back to A and B