107. Binary Search in Sorted Array

#include <stdio.h>
#include <stdint.h>
/*
* 5 10 15 20 25 30, n = 6, key = 20
-> l = 0, r = 5 -> m = 2
-> a[2] = 15 < 20 -> l = 2 + 1 = 3 
m = 3 + (5 - 3)/2 = 4 
-> a[4] = 25 > 20 -> r = 4 - 1 = 3 
-> l = 3, r = 3 


*/
int binary_search(uint8_t *arr, uint8_t n, uint8_t key) {
    // Your logic here
    uint8_t l = 0, r = n - 1;
    uint8_t m;

    while (l <= r) {
        m = l + (r - l) / 2;

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

    return -1;
}

int main() {
    uint8_t n, key;
    scanf("%hhu", &n);
    uint8_t arr[100];

    for (uint8_t i = 0; i < n; i++) {
        scanf("%hhu", &arr[i]);
    }
    scanf("%hhu", &key);

    int index = binary_search(arr, n, key);
    printf("%d", index);
    return 0;
}