FilesExpand file tree

 master

/

PalindromePairs.java

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

83 lines (70 loc) · 2.63 KB

 master

/

PalindromePairs.java

Copy path

Top

File metadata and controls

• Code
• Blame

83 lines (70 loc) · 2.63 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

public class PalindromePairs {

public List<List<Integer>> palindromePairs(String[] words) {

List<List<Integer>> result = new ArrayList<List<Integer>>();

for (int i = 0; i < words.length - 1; i++) {

for (int j = i + 1; j < words.length; j++) {

if (isPalindromePair(words[i], words[j])) {

result.add(Arrays.asList(i, j));

}

if (isPalindromePair(words[j], words[i])) {

result.add(Arrays.asList(j, i));

}

}

}

return result;

}

private boolean isPalindromePair(String word1, String word2) {

int len1 = word1.length();

int len2 = word2.length();

for (int l = 0, r = len1 + len2 - 1; l < r; l++, r--) {

char c1 = l < len1 ? word1.charAt(l) : word2.charAt(l - len1);

char c2 = r < len1 ? word1.charAt(r) : word2.charAt(r - len1);

if (c1 != c2) {

return false;

}

}

return true;

}

/**

public List<List<Integer>> palindromePairs2(String[] words) {

List<List<Integer>> result = new ArrayList<>();

if (words == null || words.length < 2) {

return result;

}

Map<String, Integer> map = new HashMap<String, Integer>();

for (int i = 0; i < words.length; i++) {

map.put(words[i], i);

}

for (int i = 0; i < words.length; i++) {

for (int j = 0; j <= words[i].length(); j++) {

String str1 = words[i].substring(0, j);

String str2 = words[i].substring(j);

if (isPalindrome(str1)) {

String str2rvs = new StringBuilder(str2).reverse().toString();

if (map.containsKey(str2rvs) && map.get(str2rvs) != i) {

result.add(Arrays.asList(map.get(str2rvs), i));

}

}

if (str2.length() != 0 && isPalindrome(str2)) {

String str1rvs = new StringBuilder(str1).reverse().toString();

if (map.containsKey(str1rvs) && map.get(str1rvs) != i) {

result.add(Arrays.asList(i, map.get(str1rvs)));

}

}

}

}

return result;

}

private boolean isPalindrome(String str) {

int left = 0;

int right = str.length() - 1;

while (left <= right) {

if (str.charAt(left++) != str.charAt(right--)) return false;

}

return true;

}

*/

}