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Commit 41af90b

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author
陈世伟
committed
feat: 2021年05月12日18:59:59
1 parent 3496407 commit 41af90b

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11 files changed

+457
-7
lines changed

11 files changed

+457
-7
lines changed

‎leetcode/0105/build_tree.go‎ renamed to ‎leetcode/105.从前序与中序遍历序列构造二叉树/build_tree.go‎

Lines changed: 13 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
package _105
1+
package _05_从前序与中序遍历序列构造二叉树
22

33
/**
44
* Definition for a binary tree node.
@@ -23,25 +23,33 @@ func buildTree(preorder []int, inorder []int) *TreeNode {
2323
return nil
2424
}
2525

26+
rootVal := preorder[0]
2627
rootNode := &TreeNode{
27-
Val: preorder[0],
28+
Val: rootVal,
2829
Left: nil,
2930
Right: nil,
3031
}
32+
preorder = preorder[1:]
3133

3234
// 找到根节点在中序遍历的位置
3335
// 根据中序遍历的特性 root节点左边的都是root节点的左子树,数量为(rootIndex+1)
3436
var rootIndex int
3537

3638
for i, v := range inorder {
37-
if v == preorder[0] {
39+
if v == rootVal {
3840
rootIndex = i
3941
break
4042
}
4143
}
4244

45+
leftInorder := inorder[:rootIndex]
46+
rightInorder := inorder[rootIndex+1:]
47+
48+
leftPreorder := preorder[:len(leftInorder)]
49+
rightPreorder := preorder[len(leftInorder):]
50+
4351
// 前序遍历的根节点的后面是左子树,左子树的切片为(1:rootIndex+1)
44-
rootNode.Left = buildTree(preorder[1:rootIndex+1], inorder[:rootIndex])
45-
rootNode.Right = buildTree(preorder[rootIndex+1:], inorder[rootIndex+1:])
52+
rootNode.Left = buildTree(leftPreorder, leftInorder)
53+
rootNode.Right = buildTree(rightPreorder, rightInorder)
4654
return rootNode
4755
}

‎leetcode/0105/build_tree_test.go‎ renamed to ‎leetcode/105.从前序与中序遍历序列构造二叉树/build_tree_test.go‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
package _105
1+
package _05_从前序与中序遍历序列构造二叉树
22

33
import (
44
"reflect"
@@ -45,7 +45,7 @@ func Test_buildTree(t *testing.T) {
4545
}
4646
for _, tt := range tests {
4747
t.Run(tt.name, func(t *testing.T) {
48-
if got := buildTree(tt.args.preorder, tt.args.inorder); !reflect.DeepEqual(got, tt.want) {
48+
if got := buildTree1(tt.args.preorder, tt.args.inorder); !reflect.DeepEqual(got, tt.want) {
4949
t.Errorf("buildTree() = %v, want %v", got, tt.want)
5050
}
5151
})
Lines changed: 45 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,45 @@
1+
package _06_从中序与后序遍历序列构造二叉树
2+
3+
/**
4+
* Definition for a binary tree node.
5+
* type TreeNode struct {
6+
* Val int
7+
* Left *TreeNode
8+
* Right *TreeNode
9+
* }
10+
*/
11+
type TreeNode struct {
12+
Val int
13+
Left *TreeNode
14+
Right *TreeNode
15+
}
16+
17+
func buildTree(inorder []int, postorder []int) *TreeNode {
18+
if len(postorder) == 0 {
19+
return nil
20+
}
21+
// 从后序遍历获取root
22+
rootVal := postorder[len(postorder)-1]
23+
root := &TreeNode{
24+
Val: rootVal,
25+
}
26+
if len(postorder) == 1 {
27+
return root
28+
}
29+
// 从后序遍历删除root
30+
postorder = postorder[:len(postorder)-1]
31+
32+
// 获取root在中序遍历的位置
33+
var rootIdx int
34+
for i := 0; i < len(inorder); i++ {
35+
if inorder[i] == rootVal {
36+
rootIdx = i
37+
break
38+
}
39+
}
40+
41+
// root在中序遍历的位置切分左右子树,后续根据前序切分的数组长度切分后续数组
42+
root.Left = buildTree(inorder[:rootIdx], postorder[:len(inorder[:rootIdx])])
43+
root.Right = buildTree(inorder[rootIdx+1:], postorder[len(inorder[:rootIdx]):])
44+
return root
45+
}
Lines changed: 46 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,46 @@
1+
package _06_从中序与后序遍历序列构造二叉树
2+
3+
import (
4+
"log"
5+
"reflect"
6+
"testing"
7+
)
8+
9+
func Test_buildTree(t *testing.T) {
10+
type args struct {
11+
inorder []int
12+
postorder []int
13+
}
14+
tests := []struct {
15+
name string
16+
args args
17+
want *TreeNode
18+
}{
19+
{name: `中序遍历 inorder = [9,3,15,20,7]
20+
后序遍历 postorder = [9,15,7,20,3]`, args: struct {
21+
inorder []int
22+
postorder []int
23+
}{inorder: []int{9, 3, 15, 20, 7}, postorder: []int{9, 15, 7, 20, 3}}},
24+
}
25+
for _, tt := range tests {
26+
t.Run(tt.name, func(t *testing.T) {
27+
got := buildTree(tt.args.inorder, tt.args.postorder)
28+
if !reflect.DeepEqual(got, tt.want) {
29+
t.Errorf("buildTree() = %v, want %v", got, tt.want)
30+
}
31+
32+
InEach(got)
33+
})
34+
}
35+
}
36+
37+
func InEach(root *TreeNode) {
38+
if root == nil {
39+
return
40+
}
41+
InEach(root.Left)
42+
log.Println(root.Val)
43+
InEach(root.Right)
44+
45+
return
46+
}
Lines changed: 32 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,32 @@
1+
package _12_路径总和
2+
3+
/**
4+
* Definition for a binary tree node.
5+
* type TreeNode struct {
6+
* Val int
7+
* Left *TreeNode
8+
* Right *TreeNode
9+
* }
10+
*/
11+
12+
type TreeNode struct {
13+
Val int
14+
Left *TreeNode
15+
Right *TreeNode
16+
}
17+
18+
func hasPathSum(root *TreeNode, targetSum int) bool {
19+
if root == nil {
20+
return false
21+
}
22+
23+
if isLeafNode(root) && root.Val == targetSum {
24+
return true
25+
}
26+
27+
return hasPathSum(root.Left, targetSum-root.Val) || hasPathSum(root.Right, targetSum-root.Val)
28+
}
29+
30+
func isLeafNode(node *TreeNode) bool {
31+
return node != nil && node.Left == nil && node.Right == nil
32+
}
Lines changed: 40 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,40 @@
1+
package _12_路径总和
2+
3+
import "testing"
4+
5+
func Test_hasPathSum(t *testing.T) {
6+
type args struct {
7+
root *TreeNode
8+
targetSum int
9+
}
10+
tests := []struct {
11+
name string
12+
args args
13+
want bool
14+
}{
15+
{name: `输入:root = [1,2,3], targetSum = 5
16+
输出:false`, args: args{
17+
root: &TreeNode{
18+
Val: 1,
19+
Left: &TreeNode{
20+
Val: 2,
21+
Left: nil,
22+
Right: nil,
23+
},
24+
Right: &TreeNode{
25+
Val: 3,
26+
Left: nil,
27+
Right: nil,
28+
},
29+
},
30+
targetSum: 5,
31+
}},
32+
}
33+
for _, tt := range tests {
34+
t.Run(tt.name, func(t *testing.T) {
35+
if got := hasPathSum(tt.args.root, tt.args.targetSum); got != tt.want {
36+
t.Errorf("hasPathSum() = %v, want %v", got, tt.want)
37+
}
38+
})
39+
}
40+
}
Lines changed: 52 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,52 @@
1+
package _13_路径总和II
2+
3+
/**
4+
* Definition for a binary tree node.
5+
* type TreeNode struct {
6+
* Val int
7+
* Left *TreeNode
8+
* Right *TreeNode
9+
* }
10+
*/
11+
type TreeNode struct {
12+
Val int
13+
Left *TreeNode
14+
Right *TreeNode
15+
}
16+
17+
func pathSum(root *TreeNode, targetSum int) [][]int {
18+
if root == nil {
19+
return nil
20+
}
21+
22+
var result [][]int
23+
24+
var each func(node *TreeNode, targetSum int, nums []int)
25+
26+
each = func(node *TreeNode, targetSum int, nums []int) {
27+
if node == nil {
28+
return
29+
}
30+
31+
newSums := make([]int, len(nums), cap(nums))
32+
copy(newSums, nums)
33+
34+
if IsLeafNode(node) && targetSum == node.Val {
35+
result = append(result, append(newSums, node.Val))
36+
return
37+
}
38+
39+
each(node.Left, targetSum-node.Val, append(newSums, node.Val))
40+
each(node.Right, targetSum-node.Val, append(newSums, node.Val))
41+
}
42+
each(root, targetSum, []int{})
43+
44+
return result
45+
}
46+
47+
func IsLeafNode(node *TreeNode) bool {
48+
if node == nil {
49+
return false
50+
}
51+
return node.Left == nil && node.Right == nil
52+
}
Lines changed: 88 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,88 @@
1+
package _13_路径总和II
2+
3+
import (
4+
"reflect"
5+
"testing"
6+
)
7+
8+
func Test_pathSum(t *testing.T) {
9+
type args struct {
10+
root *TreeNode
11+
targetSum int
12+
}
13+
tests := []struct {
14+
name string
15+
args args
16+
want [][]int
17+
}{
18+
{name: `输入:root = [5,4,8,11,null,13,4,7,2,null,null,5,1], targetSum = 22
19+
输出:[[5,4,11,2],[5,8,4,5]]`, args: args{
20+
root: &TreeNode{
21+
Val: 5,
22+
Left: &TreeNode{
23+
Val: 4,
24+
Left: &TreeNode{
25+
Val: 11,
26+
Left: &TreeNode{
27+
Val: 7,
28+
Left: nil,
29+
Right: nil,
30+
},
31+
Right: &TreeNode{
32+
Val: 2,
33+
Left: nil,
34+
Right: nil,
35+
},
36+
},
37+
Right: nil,
38+
},
39+
Right: &TreeNode{
40+
Val: 8,
41+
Left: &TreeNode{
42+
Val: 13,
43+
Left: nil,
44+
Right: nil,
45+
},
46+
Right: &TreeNode{
47+
Val: 4,
48+
Left: &TreeNode{
49+
Val: 5,
50+
Left: nil,
51+
Right: nil,
52+
},
53+
Right: &TreeNode{
54+
Val: 1,
55+
Left: nil,
56+
Right: nil,
57+
},
58+
},
59+
},
60+
},
61+
targetSum: 22,
62+
}, want: [][]int{{5, 4, 11, 2}, {5, 8, 4, 5}}},
63+
{name: `输入:root = [1,2,3], targetSum = 5
64+
输出:[]`, args: args{
65+
root: &TreeNode{
66+
Val: 1,
67+
Left: &TreeNode{
68+
Val: 2,
69+
Left: nil,
70+
Right: nil,
71+
},
72+
Right: &TreeNode{
73+
Val: 3,
74+
Left: nil,
75+
Right: nil,
76+
},
77+
},
78+
targetSum: 5,
79+
}},
80+
}
81+
for _, tt := range tests {
82+
t.Run(tt.name, func(t *testing.T) {
83+
if got := pathSum(tt.args.root, tt.args.targetSum); !reflect.DeepEqual(got, tt.want) {
84+
t.Errorf("pathSum() = %v, want %v", got, tt.want)
85+
}
86+
})
87+
}
88+
}
Lines changed: 30 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,30 @@
1+
package _04_左叶子之和
2+
3+
/**
4+
* Definition for a binary tree node.
5+
* type TreeNode struct {
6+
* Val int
7+
* Left *TreeNode
8+
* Right *TreeNode
9+
* }
10+
*/
11+
type TreeNode struct {
12+
Val int
13+
Left *TreeNode
14+
Right *TreeNode
15+
}
16+
17+
func sumOfLeftLeaves(root *TreeNode) int {
18+
if root == nil {
19+
return 0
20+
}
21+
left := sumOfLeftLeaves(root.Left)
22+
right := sumOfLeftLeaves(root.Right)
23+
// 是否是有效的左叶子节点
24+
var mid int
25+
if root.Left != nil && root.Left.Left == nil && root.Left.Right == nil {
26+
mid = root.Left.Val
27+
}
28+
29+
return mid + left + right
30+
}

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