I'd first like to note that this discussion thread is about a Java solution, and somebody just randomly posted a Python solution in it to demonstrate that the solution could be done without nesting loops (which is not an argument that anyone was making).

1. Sure, Python is an easy to use and arguably powerful--I never said it wasn't; however, the use of dynamic language magic tends to make things slow, which one of the many reasons Python is generally referred to as a slow language (though improvements have been made over the last 15 years). I'm really not sure what you are using to benchmark but, though Java has a high startup cost, it will almost always execute faster than Python.
2. As data sets get large, memory is always a constraint; saving n^2 values to an array when only 2n are needed is not a scalable solution.
3. Please re-read my comment, as I did not contradict my own point at all. Saving a value from an input stream to a single register (which is an optimization any good compiler should make on this code) and then repeatedly overwriting it is not in any way the same as reading the n^2 values as a chunk, breaking the chunk down into n^2 components, storing n^2 values, and reloading and summing the 2n you actually need.
4. The purpose of my comment was simply to point out that the same solution is accomplishable in Java, because your comment incorrectly stated that Java couldn't read and break up a line the way that Python can and implied that is what makes Python a powerful tool. So I wrote a Java version of the Python poster's code, and pointed out why I still deem it not a good or scalable solution.

#!/bin/python

import sys


'''
n = int(raw_input().strip())
a = []
for a_i in xrange(n):
    a_temp = map(int,raw_input().strip().split(' '))
    a.append(a_temp)
z1,z2 = 0,0
for x1 in range(n):    
    z1 += a[x1][x1]
for x1 in range(n):
    z2 += a[x1][n-x1-1]

print z1,z2
'''
n = int(input().strip())
dSumLeft = 0
dSumRight = 0
for i in range(n):
    matrixRow = input().split()
    dSumLeft += int(matrixRow[i])
    dSumRight += int(matrixRow[-(i + 1)])
print dSumLeft-dSumRight

neither my code , nor yours is printing, please point the error

hi i am a beginner in python can anyone explain me , how have they input 2D list in Python from the user ....

for a_i in range(n): a_t = [int(a_temp) for a_temp in input().strip().split(' ')] a.append(a_t)

That python code was brilliant

I like it. It was similar to mine in that there isn't a nested for loop iterating over multi dimensional array. My solution is unfortunately more pedantic and incurs looping twice.

//first diagonal
int fd = 0;
for (int i=0; i < n; i++) {
	fd += a[i][i];
}

//second diagonal
int sd = 0;
int x = 0;
int y = n-1;
for (int j=0; j < n; j++) {
	sd += a[x++][y--];
}        

int answer = Math.abs(sd-fd);
System.out.println(answer);

Let's say you have "1,2,3,hello" and you call .split(","). This will give you back an array of ["1", "2", "3", "hello"].

Thnx a lot