Find Index in a sorted array

/*** 11.3
Given a sorted array of n integers that has been rotated an unknown number of times,
write code to find an element in the array. You may assume that the array was originally sorted in increasing order.
EXAMPLE
Input: find 5 in {15, 16, 19, 20, 25, 1, 3, 4, 5, 7, 10, 14}
Output: 8(the index of 5 in array)
***/

#include<iostream>

using namespace std;

int findIndex(int *a, int val, int begin, int end) {
    if(begin > end) {
        return -1;
    }       
    int mid = (begin + end) / 2;
    if(a[mid] == val) return mid;

    if(a[mid] > a[begin]) {
        if (a[begin] <= val && a[mid] > val)
            return findIndex(a, val, begin, mid-1);
        else findIndex(a, val, mid+1, end);
    } else if (a[mid] < a[begin])
    {
        if(a[begin] <= val || a[mid] > val)
            return findIndex(a, val, begin, mid-1);
        else findIndex(a, val, mid+1, end);
    } else {
        if (a[mid] != a[end])
            return findIndex(a, val, mid+1, end);
        else {
            int left = findIndex(a, val, begin, mid-1);
            int right = findIndex(a, val, mid+1, end);
            if (left != -1) return left;
            else return right;
        }
    }
}

void main() {
    int a[] = {15, 16, 19, 20, 25, 1, 3, 4, 5, 7, 10, 14};
    int sz = sizeof(a) / sizeof(int);
    int index = findIndex(a, 5, 0, sz-1);
    cout<<index<<endl;

}

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