FilesExpand file tree

 master

/

MajorityElement169.java

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

70 lines (61 loc) · 1.85 KB

 master

/

MajorityElement169.java

Copy path

Top

File metadata and controls

• Code
• Blame

70 lines (61 loc) · 1.85 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

/**

* Given an array of size n, find the majority element. The majority element is

* the element that appears more than ⌊ n/2 ⌋ times.

*

* You may assume that the array is non-empty and the majority element always

* exist in the array.

*/

public class MajorityElement169 {

public int majorityElement(int[] nums) {

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

int N = nums.length;

for (int i=0; i<N; i++) {

map.put(nums[i], map.getOrDefault(nums[i], 0)+1);

if (map.get(nums[i]) > (N/2)) {

return nums[i];

}

}

return nums[0];

}

/**

* https://discuss.leetcode.com/topic/8692/o-n-time-o-1-space-fastest-solution

* Moore voting algorithm

*/

public int majorityElement2(int[] num) {

int major=num[0], count = 1;

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

if(count==0){

count++;

major=num[i];

}else if(major==num[i]){

count++;

}else count--;

}

return major;

}

/**

* https://discuss.leetcode.com/topic/28601/java-solutions-sorting-hashmap-moore-voting-bit-manipulation

* Sorting

*/

public int majorityElement3(int[] num) {

Arrays.sort(num);

return num[num.length/2];

}

/**

* https://discuss.leetcode.com/topic/28601/java-solutions-sorting-hashmap-moore-voting-bit-manipulation

* Bit manipulation

*/

public int majorityElement4(int[] nums) {

int[] bit = new int[32];

for (int num: nums)

for (int i=0; i<32; i++)

if ((num>>(31-i) & 1) == 1)

bit[i]++;

int ret=0;

for (int i=0; i<32; i++) {

bit[i]=bit[i]>nums.length/2?1:0;

ret += bit[i]*(1<<(31-i));

}

return ret;

}

}