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Palindrome Pairs.java
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54 lines (44 loc) · 1.57 KB
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class Solution {
public List<List<Integer>> palindromePairs(String[] words) {
List<List<Integer>> lists = new ArrayList<>();
Map<String, Integer> map = new HashMap<>();
for (int i=0; i<words.length; i++) {
map.put(new StringBuilder(words[i]).reverse().toString(), i);
}
if (map.containsKey("")) {
for (int i = 0; i < words.length; i++) {
if (i == map.get("")) {
continue;
}
if (palindromeCheck(words[i])) {
lists.add(Arrays.asList(map.get(""), i));
}
}
}
for (int i=0; i<words.length; i++) {
for (int j=0; j<words[i].length(); j++) {
String leftPart = words[i].substring(0, j);
String rightPart = words[i].substring(j);
if (map.containsKey(leftPart) && palindromeCheck(rightPart) && map.get(leftPart) != i) {
lists.add(Arrays.asList(i, map.get(leftPart)));
}
if (map.containsKey(rightPart) && palindromeCheck(leftPart) && map.get(rightPart) != i) {
lists.add(Arrays.asList(map.get(rightPart), i));
}
}
}
return lists;
}
private boolean palindromeCheck(String word) {
int i = 0;
int j = word.length() - 1;
while (i < j) {
if (word.charAt(i) != word.charAt(j)) {
return false;
}
i++;
j--;
}
return true;
}
}