leetcode-study/minimum-window-substring/Tessa1217.java at main · DaleStudy/leetcode-study · GitHub

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import java.util.HashMap;

import java.util.Map;

class Solution {

// 시간복잡도: O(n), 공간복잡도 O(1)

public String minWindow(String s, String t) {

int strLength = s.length();

int targetLength = t.length();

// 목표 분자열이 주어진 문자열보다 길다면 부분 문자열로 볼 수 없음

if (targetLength > strLength) {

return "";

}

// 목표 문자열에 필요한 문자와 그 개수를 담는 맵

Map<Character, Integer> charMap = new HashMap<>();

for (char c : t.toCharArray()) {

charMap.put(c, charMap.getOrDefault(c, 0) + 1);

}

// 투 포인터 선언

int left = 0;

int right = 0;

int minWindowLength = Integer.MAX_VALUE;

int minWindowStart = 0; // 최소 윈도우 시작 위치

int remaining = targetLength;

while (right < strLength) {

Character end = s.charAt(right);

if (charMap.containsKey(end)) {

charMap.put(end, charMap.get(end) - 1);

if (charMap.get(end) >= 0) {

remaining--;

}

// target 문자열의 모든 문자를 찾았다면 left 포인터 이동하면서

// 최소 윈도우 찾기 시작

while (remaining == 0) {

if (right - left + 1 < minWindowLength) {

minWindowLength = right - left + 1;

minWindowStart = left;

}

char startChar = s.charAt(left);

if (charMap.containsKey(startChar)) {

charMap.put(startChar, charMap.get(startChar) + 1);

if (charMap.get(startChar) > 0) {

remaining++;

}

left++;

}

right++;

}

return minWindowLength == Integer.MAX_VALUE ? ""

: s.substring(minWindowStart, minWindowStart + minWindowLength);

}

leetcode-study/minimum-window-substring/Tessa1217.java at main · DaleStudy/leetcode-study · GitHub

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leetcode-study/minimum-window-substring/Tessa1217.java at main · DaleStudy/leetcode-study · GitHub

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