# C++ Program to find the maximum subarray sum O(n^2) time (naive method)

We shall develop a C++ program to find the maximum subarray sum O(n^2) time (naive method).

## Algorithm

Begin
Take the array elements as input.
Make a loop for the length of the sub-array from 1 to n, within this loop,
Make another loop nested with the previous one, calculate the sum of first sub-array of that length.
For remaining sub-array sum, add the next element to the sum and subtract the first element of that sub-array.
Compare it with the global max and update if found out to be more.
Print the max sub-array and their sum as a result.
End.

## Example Code

#include<iostream>
using namespace std;
int main() {
int n, i, j, m=-1, s, ini_m, fi_m;
cout<<"\nEnter the number of data element in the array: ";
cin>>n;
int a[n];
for(i = 0; i < n; i++) {
cout<<"Enter element "<<i+1<<": ";
cin>>a[i];
}
for(i = 1; i < n+1; i++) {
s = 0;
for(j = 0; j < n; j++) {
if(j < i)
s += a[j];
else
s = s+a[j]-a[j-i];
if(m< s) {
ini_m = j-i+1;
fi_m = j;
m = s;
}
}
}
cout<<"\nThe maximum sub array is: ";
for(i = ini_m; i <= fi_m; i++)
cout<<a[i]<<" ";
cout<<"\nThe maximum sub-array sum is: "<<m;
}

## Output

Enter the number of data element in the array: 10
Enter element 1: 1
Enter element 2: -2
Enter element 3: 3
Enter element 4: -4
Enter element 5: 5
Enter element 6: -6
Enter element 7: 7
Enter element 8: 8
Enter element 9: -9
Enter element 10: 10
The maximum sub array is: 7 8 -9 10
The maximum sub-array sum is: 16