Challenge

Given 10000000 random 8bit signed integers, create the fastest program to sum them.
Assembly not allowed. Time is counted only at the process of summation.

Do your own homework.

(apply + integers)

Fastest to write.

>>2
This.
/prog/ challenges should not be thinly-veiled homework help threads.

Honestly, if you need to consult the internet for your homework, you're not cut out for programming anyway. Just learn to do it on your own. Having someone do your work might help you for an individual assignment, and ultimately help your class's grade, but it won't help you personally understand anything.

enterprise-level C, this should run in O(log(n))


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define LENGTH 10000000
#define MAX 128

int sum(int* arr, int len)
{
    if(len == 2)
        return (arr[0] + arr[1]);
    else if(len == 1)
        return arr[0];
    else
    {
        int len1 = (len / 2), len2 = (len / 2) + (len % 2);
        int* arr1 = (int*) malloc(sizeof(int) * len1);
        int* arr2 = (int*) malloc(sizeof(int) * len2);
        memcpy(arr1, arr, sizeof(int) * len1);
        memcpy(arr2, (arr + len1), sizeof(int) * len2);
        int toReturn = sum(arr1, len1) + sum(arr2, len2);
        free(arr1);
        free(arr2);
        return toReturn;
    }
}

int main()
{
    int* arr = (int*) malloc(sizeof(int) * LENGTH);

    for(int i = 0; i < LENGTH; i++)
        arr[i] = rand() % MAX;

    printf("Sum is: %d", sum(arr, LENGTH));
    free(arr);
    return 0;
}

>>5
OPTIMIZED enterprise-level C


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define LENGTH 10000000
#define MAX 128

int sum(int* arr, int len)
{
    if(len == 2)
        return (arr[0] + arr[1]);
    else if(len == 1)
        return arr[0];
    else
    {
        int len1 = (len / 2), len2 = (len / 2) + (len % 2);
        return (sum(arr, len1) + sum(arr + len1, len2));
    }
}

int main()
{
    int* arr = (int*) malloc(sizeof(int) * LENGTH);

    for(int i = 0; i < LENGTH; i++)
        arr[i] = rand() % MAX;

    printf("Sum is: %d", sum(arr, LENGTH));
    free(arr);
    return 0;
}

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