Count And Say

CountAndSay.java

import java.util.*;

public class Solution {

    public String countAndSay(int n) {
        List<Integer> i = new ArrayList<Integer>();
        i.add(1);

        while (--n > 0) {
            i = say(i);
        }

        StringBuilder sb = new StringBuilder();
        for (int ii : i) {
            sb.append(ii);
        }
        return sb.toString();
    }
    
    public List<Integer> say(List<Integer> input) {
        final List<Integer> result = new ArrayList<Integer>();
        int last = input.get(0);
        int count = 1;
        for (int i=0; i<input.size()-1; ++i) {
            if (input.get(i+1) != last) {
                result.add(count);
                result.add(last);
                count=1;
                last=input.get(i+1);
            } else {
                count++;
            }
        }
        result.add(count);
        result.add(last);
        return result;
    }
    
    public List<Integer> encode(int i) {
        List<Integer> result = new ArrayList<Integer>();
        while (i > 0) {
            result.add(i % 10);
            i = i / 10;
        }
        java.util.Collections.reverse(result);
        return result;
    }
}