[Python][프로그래머스] 보석 쇼핑

#2020카카오인턴십 문제

from collections import Counter

def solution(gems):
    ans = [0,len(gems)]
    n = len(set(gems))
    i,j = 0,n # i,j커서를 움직임. j는 최소길이 n부터 시작
    sets = Counter(gems[i:j]) # count sets
    
    while (i >= 0 and j < len(gems)):
        if len(sets) == n:
            if j-i < ans[1]-ans[0]:
                ans = [i,j]
            else:
                sets[gems[i]] -= 1
                if sets[gems[i]] == 0:
                    del sets[gems[i]]
                i += 1
        else:
            k = gems[j]
            j += 1
            if k not in sets:
                sets[k] = 1
            else:
                sets[k] += 1
    return [ans[0]+1, ans[1]]