BiSortedArray

#include <iostream>

using namespace std;

int A[] = {1, 3, 8, 12, 4, 2}, Size = 0; // Will update size in main

// Get the transition index
int findTransition() {
    int left = 0, right = Size - 1;

    while (left < right) {
        int mid = left + (right - left) / 2;

        if (A[mid] > A[mid + 1]) {
            right = mid; // Move to left subarray
        } else {
            left = mid + 1; // Move to right subarray
        }
    }

    return left;
}

// Binary Search on increasing subarray
int increasingBinarySearch(int left, int right, int x) {
    while (left <= right) {
        int mid = left + (right - left) / 2;

        if (A[mid] == x)
            return mid;
        if (A[mid] < x)
            left = mid + 1;
        else
            right = mid - 1;
    }

    return -1;
}

// Binary Search on decreasing subarray
int decreasingBinarySearch(int left, int right, int x) {
    while (left <= right) {
        int mid = left + (right - left) / 2;

        if (A[mid] == x)
            return mid;
        if (A[mid] > x)
            left = mid + 1;
        else
            right = mid - 1;
    }

    return -1;
}

// Function to search x in a BiSorted array
int biSortedArraySearch(int x) {
    int transition = findTransition();
    cout<<"Transition Index: "<<transition<<endl;

    // Search in the increasing part
    int result = increasingBinarySearch(0, transition-1, x);

    if (result != -1)
        return result;
    else
        // Search in the decrasing part
        return decreasingBinarySearch(transition, Size - 1, x);
}

int main() {

    Size = sizeof(A) / sizeof(A[0]);
    int x = 0;
    int result = biSortedArraySearch(x);
    if (result != -1) {
        cout << "Element " << x << " found at index " << result << endl;
    } else {
        cout << "Element " << x << " not found." << endl;
    }

    return 0;
}