Class Solution

LongestHappyString.java:1–43

class Solution {
    public String longestDiverseString(int a, int b, int c) {
        // create a pq (decreasing order of element count)
        PriorityQueue<Pair> pq = new PriorityQueue<>();
        if(a>0){
            pq.offer(new Pair(a,'a'));
        }
        if(b>0){
            pq.offer(new Pair(b,'b'));
        }
        if(c>0){
            pq.offer(new Pair(c,'c'));
        }

        StringBuilder res = new StringBuilder();
        while(!pq.isEmpty()){
            Pair node = pq.poll();
            int n = res.length(); 
            char ch = node.ch;
            int count = node.count;
            // if current element is same as last two then push the second highest freq
            // element
            if(n>=2 && res.charAt(n-1) == ch && res.charAt(n-2) == ch) {
                // if sec highest freq element is not present then break
                if(pq.isEmpty()) break;
                Pair sec = pq.poll();
                res.append(sec.ch);
                sec.count--;
                if(sec.count>0){
                    pq.offer(new Pair(sec.count,sec.ch));
                }
            }else{
                res.append(node.ch);
                node.count--;
            }
            // if element count is not 0, insert in pq with updated count
            if(node.count>0){
                pq.offer(new Pair(node.count,node.ch));
            }
        }
        return res.toString();
    }
}


class Pair implements Comparable<Pair> {