Twitter puzzle by Michael Kozakov

gistfile1.java

http://qandwhat.apps.runkite.com/i-failed-a-twitter-interview/
https://gist.github.com/mkozakov/59af0fd5bddbed1a0399

My solution:

public class Ideone {

	public static void main(String[] args) {
		int[] myIntArray = {2, 5, 1, 3, 1, 2, 1, 7, 7, 6};
		
//	Author's call	      		
		System.out.println(calculateVolume(myIntArray));
		
// 	My call		
		System.out.println(mycalculateVolume(myIntArray));

	}
	
//	Author's solution
	public static int calculateVolume(int[] land) {
		int leftMax = 0;
		int rightMax = 0;
		int left = 0;
		int right = land.length - 1;
		int volume = 0;
		
		while(left < right) {
			if(land[left] > leftMax) {
				leftMax = land[left];
			}
			if(land[right] > rightMax) {
				rightMax = land[right];
			}
			if(leftMax >= rightMax) {
				volume += rightMax - land[right];
				right--;
			} else {
				volume += leftMax - land[left];
				left++;
			}
		}
		return volume;
	}
	
// 	My solution (but unfortunately it doesn't work for [2, 5, 1, 2, 3, 4, 7, 5, 6] which should give 11):
	public static int mycalculateVolume(int[] land) {
		int leftMax = 0;
		int subvolume = 0;
		int volume = 0;
		
		for (int index = 0; index < land.length; index++) {
			if (land[index] >= leftMax){
				leftMax = land[index];  
				volume = volume + subvolume;
				subvolume = 0;
			}
			else {
				subvolume = subvolume + leftMax - land[index];
			}
		}
		return volume;
	}
	
	// 	My solution, plan B in progress:
	
	http://it.laplit.com/index.php/humanoid-blog/128-article-7
}