//To find the length of longest zig-zag subsequence
#include <stdio.h>
#include <stdlib.h>

// function to return max of two numbers
int max(int a, int b) {  return (a > b) ? a : b; }

// Function to return longest Zig-Zag subsequence length
int zzis(int arr[], int n)
{
    /*Z[i][0] = Length of the longest Zig-Zag subsequence
          ending at index i and last element is greater
          than its previous element
     Z[i][1] = Length of the longest Zig-Zag subsequence
          ending at index i and last element is smaller
          than its previous element   */
    int Z[n][2];

    /* Initialize all values from 1  */
    for (int i = 0; i < n; i++)
        Z[i][0] = Z[i][1] = 1;

    int res = 1; // Initialize result

    /* Compute values in bottom up manner */
    for (int i = 1; i < n; i++)
    {
        // Consider all elements as previous of arr[i]
        for (int j = 0; j < i; j++)
        {
            // If arr[i] is greater, then check with Z[j][1]
            if (arr[j] < arr[i] && Z[i][0] < Z[j][1] + 1)
                Z[i][0] = Z[j][1] + 1;

            // If arr[i] is smaller, then check with Z[j][0]
            if( arr[j] > arr[i] && Z[i][1] < Z[j][0] + 1)
                Z[i][1] = Z[j][0] + 1;
        }

        /* Pick maximum of both values at index i  */
        if (res < max(Z[i][0], Z[i][1]))
            res = max(Z[i][0], Z[i][1]);
    }

    return res;
}

/* Driver program */
int main()
{
    int arr[] = { 10, 22, 9, 33, 49, 50, 31, 60 };
    int n = sizeof(arr)/sizeof(arr[0]);
    printf("Length of Longest Zig-Zag subsequence is %d\n",
            zzis(arr, n) );
    return 0;
}