programmers_징검다리 건너기_java

https://school.programmers.co.kr/learn/courses/30/lessons/64062

프로그래머스

import java.util.*;
class Solution {
    public int solution(int[] stones, int k) {
        int answer = 200000001;
        
        int stonesSize = stones.length;     
        Deque<Pair> dequeue = new ArrayDeque<>();    
        
        for(int i = 0; i< stonesSize; i++){      
            if(dequeue.isEmpty()){ // i == 0
                dequeue.offerFirst(new Pair(stones[i], i));                
            }
            
            // k 보다 큰경우 || 현재 최대값이 범위를 넘어가는 경우
            if(dequeue.size() >= k || dequeue.peekFirst().idx <= i-k){ 
                dequeue.pollFirst();
            }            
            
            
            if(!dequeue.isEmpty() && dequeue.peekFirst().num > stones[i]){   
            	// 해당 값보다 작은 값 모두 제거
                while(!dequeue.isEmpty() && stones[i] > dequeue.peekLast().num){
                    dequeue.pollLast();
                }
                dequeue.offerLast(new Pair(stones[i], i));
            }
            // 모든값 제거
            else{                
                dequeue.clear();
                dequeue.offerFirst(new Pair(stones[i], i));
            } 
            
            if(i>=k-1){
                answer = Math.min(answer, dequeue.peekFirst().num);
            }
            
            // System.out.println(i + " " + Arrays.toString(dequeue.toArray()));
            
        }

        return answer;
    }
    
    public class Pair{
        int num;
        int idx;
        public Pair(int num, int idx){
            this.num = num;
            this.idx = idx;
        }
        
        @Override
        public String toString() {
            return "{" + this.num + ", " + this.idx + "}";
        }
        
    }
}