Merge sort

 

 

 

#include <stdio.h>

void merge(int *arr, int l, int m, int r)
{

    int i, tt[r - l + 1];
    int cp = 0, lp = l, rp = m + 1;

    while(lp <= m && rp <= r) {
        if(arr[lp] < arr[rp]) tt[cp++] = arr[lp++];
        else                  tt[cp++] = arr[rp++];
    }

    while(lp <= m) tt[cp++] = arr[lp++];
    while(rp <= r) tt[cp++] = arr[rp++];

    for(i = 0; i < cp; i++) {
        arr[l + i] = tt[i];
    }

    return;
}

void merge_sort(int *arr, int l, int r)
{
    if(l < r){
        int m = (l + r) / 2;
        merge_sort(arr, l, m);
        merge_sort(arr, m + 1, r);
        merge(arr, l, m, r);
    }
}

 

int binsearch(int *arr, int size, int key)
{
    int l = 0;
    int r = size - 1;
    int m;

    while (l <= r) {
        m = (l + r) >> 1;
        if(key > arr[m]) l = m + 1;
        else if (key < arr[m]) r = m - 1;
        else return m;
    }

    return -1;
}

int main()
{
    int arr[16] = {
                   5, 11, 81, 7, 99, 77, 23, 90,
                   17, 55, 4, 188, 518, 3, 66, 110
                };

    int i, size = sizeof(arr) / sizeof(int);

    merge_sort(arr, 0, size - 1);

    for(i = 0; i < size; i++){
        printf("%d ",arr[i]);
    }
    printf("\n");

 

    i = binsearch(arr, size, 188);

    if(i != -1) printf("arr[%d] = %d\n", i, arr[i]);

 

    return 0;
}