CareerCup

package com.home.careercup;

public class GreatJailEscape {

    public static void main(String[] args) {
        System.out.println(countJumps(7, 5,2,7,8,9,12,13,14,15));
        System.out.println(countJumps(7, 5,2,4,4,4,4,4,4,4));
    }

    /*
    if up (x) <= down (y) then escape is possible if all the walls are of height <= up.
    Also, after scaling a wall successfully - a jump may be required to jump down the wall.
    This jump is not added to this count
     */
    static int countJumps (int N, int up, int down, int ...walls){
        if ( up <= down) {
            //verify if all walls have heights <=up
            for (int i = 0; i <walls.length ; i++) {
                if  (walls [i] > up) throw new RuntimeException("no escape");
            }
            return N; /* N should be same as walls.length */
        }

        int jumps = 0;
        for (int i = 0; i <N ; i++)
            jumps+=jumpcount (walls [i], up, down);
        return jumps;

    }
    /* it my be possible to simplify the below using Math.ceil */
    static int jumpcount ( int h, int up, int down){
        int j;
        if (h<= up) {
            j= 1;
        }else {
            j= h / (up-down) + (h% (up-down) > 0 ? 1 :0);
        }
        System.out.printf("wall height=%d, up=%d, down=%d, jumps=%d %n", h, up, down, j);
        return j;
    }

}

Actual jump count is

(h1+h2+h3+h4+..+hn) / (x-y)

(h1-x)/(x-y)+1+(h2-x)/(x-y)+1...+(hn-x)/(x-y)+1 or
n+(h1+h2+...+hn-n*x)/(x-y)

If one can jump from top of one wall to next wall by x feet, things would change though