Amazon find symbols score and total sum. X = multiply by 2 with previous score. + = adding previous 2 scores. Z = ignoring last score, as if it isn't thrown never.

Score.java

package algo;

public class Score {

    public static void main(String[] args) {
        String[] nums = { "5", "-2", "4", "Z", "X", "9", "+", "+" }; // 27
        // String[] nums = { "1", "2", "4", "Z"}; // 3
        System.out.println(findScore(nums, nums.length));
    }

    static int findScore(String[] blocks, int length) {
        int sum = 0;
        int[] score = new int[length];

        for (int i = 0; i < length; i++) {

            if (blocks[i].equals("Z")) {
                if (i == 0) {
                    score[i] = 0;
                }
                if (i > 0) {
                    score[i - 1] = 0;
                }
                if (i > 1) {
                    score[i] = score[i - 2];
                    score[i - 2] = 0;
                }
            } else if (blocks[i].equals("X")) {
                score[i] = score[i - 1] * 2;
            } else if (blocks[i].equals("+")) {
                score[i] = score[i - 1] + score[i - 2];
            } else {
                score[i] = (int) Integer.valueOf(blocks[i]);
            }
        }

        for (int i = 0; i < score.length; i++) {
            sum += score[i];
        }

        return sum;
    }

}