package leetcode.string;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class FindSubstring {
public List findSubstring(String s, String[] words) {
List result = new ArrayList<>();
//å—符串数é‡
final int wordsNum = words.length;
if (wordsNum == 0 || s.isEmpty())
return result;
//å—符串长度
final int wordLength = words[0].length();
Map wordsMap = new HashMap<>();
for (int i = 0; i < wordsNum; i++) {
int num = wordsMap.getOrDefault(words[i], 0);
num++;
wordsMap.put(words[i], num);
}
//é历å—符串
int end = s.length() - wordsNum * wordLength + 1;
for (int i = 0; i < end; i++) {
Map existMap = new HashMap<>();
int num = 0;
while (num < wordsNum) {
String word = s.substring(i + num * wordLength, i + (num + 1) * wordLength);
//如果当å‰å—符串是wordsä¸
if (wordsMap.containsKey(word)) {
//å·²ç»ç›¸ç‰
int wordNum = existMap.getOrDefault(word, 0);
if (wordNum == wordsMap.get(word)) {
break;
}
wordNum++;
existMap.put(word, wordNum);
} else {
break;
}
num++;
}
if (num == wordsNum) {
result.add(i);
}
}
return result;
}
}