forked from algorithmzuo/algorithmbasic2020
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathCode01_IndexTree.java
More file actions
83 lines (70 loc) · 1.55 KB
/
Code01_IndexTree.java
File metadata and controls
83 lines (70 loc) · 1.55 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
package class32;
public class Code01_IndexTree {
// 下标从1开始！
public static class IndexTree {
private int[] tree;
private int N;
// 0位置弃而不用！
public IndexTree(int size) {
N = size;
tree = new int[N + 1];
}
// 1~index 累加和是多少？
public int sum(int index) {
int ret = 0;
while (index > 0) {
ret += tree[index];
index -= index & -index;
}
return ret;
}
// index & -index : 提取出index最右侧的1出来
// index : 0011001000
// index & -index : 0000001000
public void add(int index, int d) {
while (index <= N) {
tree[index] += d;
index += index & -index;
}
}
}
public static class Right {
private int[] nums;
private int N;
public Right(int size) {
N = size + 1;
nums = new int[N + 1];
}
public int sum(int index) {
int ret = 0;
for (int i = 1; i <= index; i++) {
ret += nums[i];
}
return ret;
}
public void add(int index, int d) {
nums[index] += d;
}
}
public static void main(String[] args) {
int N = 100;
int V = 100;
int testTime = 2000000;
IndexTree tree = new IndexTree(N);
Right test = new Right(N);
System.out.println("test begin");
for (int i = 0; i < testTime; i++) {
int index = (int) (Math.random() * N) + 1;
if (Math.random() <= 0.5) {
int add = (int) (Math.random() * V);
tree.add(index, add);
test.add(index, add);
} else {
if (tree.sum(index) != test.sum(index)) {
System.out.println("Oops!");
}
}
}
System.out.println("test finish");
}
}