Given a number N, the task is to find the number of ways of writing N as a sum of 4 squares. Two representations are considered different if their terms are in a different order or if the integer being squared (not just the square) is different.
Input : n=1
12 + 02 + 02 + 02
02 + 12 + 02 + 02
02 + 02 + 12 + 02
02 + 02 + 02 + 12
Similarly there are 4 other possible perumutations by replacing 1 with -1
Hence there are 8 possible ways.
Jacobi’s four-square theorem states that the number of ways of writing n as a sum of 4 squares is 8 times the sum of divisor of n if n is odd and is 24 times the sum of odd divisor of n if n is even.Find the sum of odd and even divisor of n by running a loop from 1 to sqrt(n) .
Time Complexity : O(sqrt(N))
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