-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathPathInTree.java
More file actions
174 lines (146 loc) · 5.49 KB
/
Copy pathPathInTree.java
File metadata and controls
174 lines (146 loc) · 5.49 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
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
package pathInTree;
import commonDataStructures.BinaryTreeNode;
import org.junit.Test;
import java.util.Iterator;
import java.util.Stack;
import java.util.Vector;
/**
* 二叉树中和为某一值的路径
* 题目：输入一棵二叉树和一个整数，打印出二叉树中结点值的和为输入整数的所
* 有路径。从树的根结点开始往下一直到叶结点所经过的结点形成一条路径。
* Created by hxchen on 2018/7/4.
*/
public class PathInTree {
public static void findPath(BinaryTreeNode root, int total) {
if (null == root)
return;
Vector<Integer> path = new Vector<>();// vector,重要的数据结构
int currentSum = 0;
findPath(root, total, path, currentSum);
}
public static void findPath(BinaryTreeNode root, int total, Vector<Integer> path, int currentSum) {
currentSum += root.value;
path.addElement(root.value);
// 如果是叶结点，并且路径上结点的和等于输入的值
// 打印出这条路径
boolean isLeaf = (root.left == null && root.right == null);
if (currentSum == total && isLeaf) {
System.out.print("Find a path:");
Iterator<Integer> it = path.iterator();
while (it.hasNext()) {
System.out.print(it.next().intValue() + "\t");
}
}
// 如果不是叶结点，则遍历它的子结点
if (root.left != null)
findPath(root.left, total, path, currentSum);
if (root.right != null)
findPath(root.right, total, path, currentSum);
// 在返回到父结点之前，在路径上删除当前结点，并在currentSum中减去当前结点的值
path.remove(path.size() - 1);// start with 0
}
// ====================测试代码====================
void Test(String testName, BinaryTreeNode root, int expectedSum) {
if (testName != null)
System.out.format("%s begins:\n", testName);
findPath(root, expectedSum);
System.out.format("\n");
}
// 10
// / \
// 5 12
// /\
// 4 7
// 有两条路径上的结点和为22
@Test
public void Test1() {
BinaryTreeNode pNode10 = new BinaryTreeNode(10);
BinaryTreeNode pNode5 = new BinaryTreeNode(5);
BinaryTreeNode pNode12 = new BinaryTreeNode(12);
BinaryTreeNode pNode4 = new BinaryTreeNode(4);
BinaryTreeNode pNode7 = new BinaryTreeNode(7);
BinaryTreeNode.ConnectTreeNode(pNode10, pNode5, pNode12);
BinaryTreeNode.ConnectTreeNode(pNode5, pNode4, pNode7);
System.out.format("Two paths should be found in Test1.\n");
Test("Test1", pNode10, 22);
}
// 10
// / \
// 5 12
// /\
// 4 7
// 没有路径上的结点和为15
@Test
public void Test2() {
BinaryTreeNode pNode10 = new BinaryTreeNode(10);
BinaryTreeNode pNode5 = new BinaryTreeNode(5);
BinaryTreeNode pNode12 = new BinaryTreeNode(12);
BinaryTreeNode pNode4 = new BinaryTreeNode(4);
BinaryTreeNode pNode7 = new BinaryTreeNode(7);
BinaryTreeNode.ConnectTreeNode(pNode10, pNode5, pNode12);
BinaryTreeNode.ConnectTreeNode(pNode5, pNode4, pNode7);
System.out.format("No paths should be found in Test2.\n");
Test("Test2", pNode10, 15);
}
// 5
// /
// 4
// /
// 3
// /
// 2
// /
// 1
// 有一条路径上面的结点和为15
@Test
public void Test3() {
BinaryTreeNode pNode5 = new BinaryTreeNode(5);
BinaryTreeNode pNode4 = new BinaryTreeNode(4);
BinaryTreeNode pNode3 = new BinaryTreeNode(3);
BinaryTreeNode pNode2 = new BinaryTreeNode(2);
BinaryTreeNode pNode1 = new BinaryTreeNode(1);
BinaryTreeNode.ConnectTreeNode(pNode5, pNode4, null);
BinaryTreeNode.ConnectTreeNode(pNode4, pNode3, null);
BinaryTreeNode.ConnectTreeNode(pNode3, pNode2, null);
BinaryTreeNode.ConnectTreeNode(pNode2, pNode1, null);
System.out.format("One path should be found in Test3.\n");
Test("Test3", pNode5, 15);
}
// 1
// \
// 2
// \
// 3
// \
// 4
// \
// 5
// 没有路径上面的结点和为16
@Test
public void Test4() {
BinaryTreeNode pNode1 = new BinaryTreeNode(1);
BinaryTreeNode pNode2 = new BinaryTreeNode(2);
BinaryTreeNode pNode3 = new BinaryTreeNode(3);
BinaryTreeNode pNode4 = new BinaryTreeNode(4);
BinaryTreeNode pNode5 = new BinaryTreeNode(5);
BinaryTreeNode.ConnectTreeNode(pNode1, null, pNode2);
BinaryTreeNode.ConnectTreeNode(pNode2, null, pNode3);
BinaryTreeNode.ConnectTreeNode(pNode3, null, pNode4);
BinaryTreeNode.ConnectTreeNode(pNode4, null, pNode5);
System.out.format("No paths should be found in Test4.\n");
Test("Test4", pNode1, 16);
}
// 树中只有1个结点
@Test
public void Test5() {
BinaryTreeNode pNode1 = new BinaryTreeNode(1);
System.out.format("One path should be found in Test5.\n");
Test("Test5", pNode1, 1);
}
// 树中没有结点
@Test
public void Test6() {
System.out.format("No paths should be found in Test6.\n");
Test("Test6", null, 0);
}
}