P2.c

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void main(){

    int16_t *arr, *lookup;
    long long int sum = 0, value = 0, count = 0, size = 500000000;

    arr = (int16_t*) calloc(size, sizeof(int16_t));
    lookup = (int16_t*) calloc(65535, sizeof(int16_t));

    srand(1);

    for(count = 0; count < size; count++){
        arr[count] = (rand() % 65537) - 32769;
    }

    for(count = 0; count < 65536; count++){
        value = count;
        lookup[count] = (value - 32768)  * 0.75;
    }

    clock_t begin = clock();

    for(count = 0; count < size; count++){
            value = arr[count];
        arr[count] = lookup[value + 32768];
    }

    clock_t end = clock();
    double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;

    for(count = 0; count < size; count++){
        sum += arr[count];
    }

    printf("sum is %d\n", sum);
    printf("time taken for part b was %lf\n", time_spent);

    free(arr);
    free(lookup);
}