DP14CountEncoding.java

import java.util.*;

public class DP14CountEncoding {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String str = sc.next();
        int[] dp = new int[str.length()];
        dp[0] = 1;

        for (int i = 1; i < dp.length; i++) {
            if (str.charAt(i - 1) == '0' && str.charAt(i) == '0') {
                dp[i] = 0;
            } else if (str.charAt(i - 1) == '0') {
                dp[i] = dp[i - 1];
            } else if (str.charAt(i) == '0') {
                if (str.charAt(i - 1) == '1' || str.charAt(i - 1) == '2') {
                    dp[i] = (i >= 2 ? dp[i - 2] : 1);
                } else {
                    dp[i] = 0;
                }
            } else {
                if (Integer.parseInt(str.substring(i - 1, i + 1)) <= 26) {
                    dp[i] = dp[i - 1] + (i >= 2 ? dp[i - 2] : 1);
                } else {
                    dp[i] = dp[i - 1];
                }
            }
        }
        System.out.println(dp[str.length() - 1]);
    }
}