Coding 공부

def changeSeconds(times):
    return  sum(int(x) * 60 ** i for i, x in enumerate(reversed(times.split(':'))))
def changeString(times):
    hour = times//3600
    minute = (times-hour*3600)//60
    seconds = times%60
    return "%02d:%02d:%02d"%(hour,minute,seconds)

def solution(play_time, adv_time, logs):
    answer = ''
    play_time =  changeSeconds(play_time)
    adv_time = changeSeconds(adv_time)
    time_laps = [0]*(play_time+1)
    for timeString in logs:
        start_time,end_time = map(changeSeconds, timeString.split('-'))
        time_laps[start_time] += 1
        time_laps[end_time] -= 1

    for ind in range(1,play_time+1):
        time_laps[ind] += time_laps[ind-1]
    max_times = sum(time_laps[:adv_time])
    max_start_time = 0
    current_sum_times = max_times
    for ind in range(1,play_time+1-adv_time):
        current_sum_times = current_sum_times - time_laps[ind-1] + time_laps[ind+adv_time-1]
        if current_sum_times > max_times:
            max_times = current_sum_times
            max_start_time = ind
    answer = changeString(max_start_time)
    return answer

구간합을 이용해 푼 방식이다.

각 start와 end_time에 각각 +1, -1을 해주고,

누적값을 해준다. 그리고 그 광고시간의 길이만큼의 sum을 해주면, 해당 시간동안 보는 광고사용자의 수가 될수 있다.

def changeSeconds(times):
    return  sum(int(x) * 60 ** i for i, x in enumerate(reversed(times.split(':'))))
def changeString(times):
    hour = times//3600
    minute = (times-hour*3600)//60
    seconds = times%60
    return "%02d:%02d:%02d"%(hour,minute,seconds)

def solution(play_time, adv_time, logs):
    answer = ''
    play_time =  changeSeconds(play_time)
    adv_time = changeSeconds(adv_time)
    time_laps = [0]*(play_time+1)
    diff = [0]*(play_time+1)
    for timeString in logs:
        start_time,end_time = map(changeSeconds, timeString.split('-'))
        diff[start_time] += 1
        diff[end_time] -= 1
    diff_count = 0
    for ind in range(1,play_time+1):
        time_laps[ind] += time_laps[ind-1] + diff_count
        diff_count += diff[ind]

    max_times = time_laps[adv_time]
    max_start_time = 0
    for ind in range(1,play_time+1-adv_time):
        if time_laps[adv_time+ind] - time_laps[ind] > max_times:
            max_times = time_laps[adv_time+ind] - time_laps[ind]
            max_start_time = ind
    answer = changeString(max_start_time)
    return answer

같은 원리이지만, sum 하는 방식을 개선을 한것이다. diff_count를 해줘서 해당구간에서 보는 인원을 누적해줘서 하는 방식이다.

# 3020 개똥벌레

N,H = map(int,input().split())

bottom_list = [0]*H
top_list = [0]*H


for ind in range(N):
    height = int(input())
    if ind%2:
        top_list[height] += 1
    else:
        bottom_list[height] += 1

for ind in range(1,H):
    bottom_list[ind] += bottom_list[ind-1]
    top_list[ind] += top_list[ind-1] 

bottom_list.append(bottom_list[-1])
top_list.append(top_list[-1])
min_result = float('inf')
min_cnt = 0
for k in range(H):
    bottom_cnt = bottom_list[-1] - bottom_list[k]
    top_cnt = top_list[-1] - top_list[(H-1)-k]
    if bottom_cnt +top_cnt < min_result:
        min_result = bottom_cnt+top_cnt
        min_cnt = 1
    elif bottom_cnt + top_cnt == min_result:
        min_cnt += 1

print(min_result,min_cnt)

prefix sum 을 이용해서 푼 방식이다.  종유석과 석순을 구분해서 prefix_sum을 해주고, 그 다음에 상황에 맞게 최저값을 구해주면 된다.

# 3020 개똥벌레
import sys


N,H = map(int,sys.stdin.readline().split())

bottom_list = [0]*(H+1)
top_list = [0]*(H+1)

for ind in range(N):
    height = int(input())
    if ind%2:
        top_list[height] += 1
    else:
        bottom_list[H-height+1] += 1
for ind in range(H-1,0,-1):
    top_list[ind] += top_list[ind+1]


for ind in range(2,H+1):
    bottom_list[ind] += bottom_list[ind-1]

min_total = N
min_cnt = 0
for ind in range(1,H+1):
    sub_sum = bottom_list[ind] + top_list[ind]
    if sub_sum < min_total:
        min_total = sub_sum
        min_cnt = 1
    elif sub_sum == min_total:
        min_cnt += 1
print(min_total,min_cnt)

이 코드는 석순의 저장 방식을 다르게 하여, 한번에 계산이 편하게 한 방식이다.