-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathhea.java
More file actions
87 lines (66 loc) · 1.95 KB
/
Copy pathhea.java
File metadata and controls
87 lines (66 loc) · 1.95 KB
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
84
85
86
87
import java.util.*;
public class hea {
static class Heap{
ArrayList<Integer> arr = new ArrayList<>();
public void add(int data){
//add at the last index
arr.add(data);
// child index
int x = arr.size()-1;
// parent index
int parent = (x-1)/2;
while(arr.get(x) < arr.get(parent)){ //O(logn)
int temp = arr.get(x);
arr.set(x, arr.get(parent));
arr.set(parent, temp);
x = parent;
parent = (x-1)/2;
}
}
public int peek(){
return arr.get(0);
}
private void heapify(int i){
int left = 2*i+1;
int right = 2*i+2;
int minIdx = i;
if(left < arr.size() && arr.get(minIdx) > arr.get(left)){
minIdx = left;
}
if(right < arr.size() && arr.get(minIdx) > arr.get(right)){
minIdx = right;
}
if(minIdx != i){
//swap
int temp = arr.get(i);
arr.set(i, arr.get(minIdx));
arr.set(minIdx, temp);
heapify(minIdx);
}
}
public int remove(){
int data = arr.get(0);
// swap
int temp = arr.get(0);
arr.set(0,arr.get(arr.size()-1));
arr.set(arr.size()-1, temp);
arr.remove(arr.size() - 1); // Remove the last element (now at root)
heapify(0);
return data;
}
public boolean isEmpty(){
return arr.size() == 0;
}
}
public static void main(String[] args) {
Heap hp = new Heap();
hp.add(3);
hp.add(4);
hp.add(1);
hp.add(5);
while (!hp.isEmpty()) {
System.out.print(hp.peek()+" ");
hp.remove();
}
}
}