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Feb 15, 2025
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feat: update solutions to lcci problems: No.04.12,08.02 #4067

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78 changes: 36 additions & 42 deletions lcci/04.12.Paths with Sum/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -70,15 +70,13 @@ edit_url: https://github.com/doocs/leetcode/edit/main/lcci/04.12.Paths%20with%20
```python
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None


# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def pathSum(self, root: TreeNode, sum: int) -> int:
def dfs(root: TreeNode, s: int):
def pathSum(self, root: Optional[TreeNode], sum: int) -> int:
def dfs(root: Optional[TreeNode], s: int) -> int:
if root is None:
return 0
s += root.val
Expand Down Expand Up @@ -145,9 +143,8 @@ class Solution {
class Solution {
public:
int pathSum(TreeNode* root, int sum) {
unordered_map<long long, int> cnt;
cnt[0] = 1;
function<int(TreeNode*, long long)> dfs = [&](TreeNode* root, long long s) {
unordered_map<long long, int> cnt{{0, 1}};
auto dfs = [&](this auto&& dfs, TreeNode* root, long long s) -> int {
if (!root) {
return 0;
}
Expand Down Expand Up @@ -285,43 +282,40 @@ impl Solution {
#### Swift

```swift
/* class TreeNode {
* var val: Int
* var left: TreeNode?
* var right: TreeNode?
*
* init(_ val: Int, _ left: TreeNode? = nil, _ right: TreeNode? = nil) {
* self.val = val
* self.left = left
* self.right = right
* }
* }
*/

/**
* Definition for a binary tree node.
* public class TreeNode {
* public var val: Int
* public var left: TreeNode?
* public var right: TreeNode?
* public init() { self.val = 0; self.left = nil; self.right = nil; }
* public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
* public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
* self.val = val
* self.left = left
* self.right = right
* }
* }
*/
class Solution {
private var cnt: [Int: Int] = [:]
private var target: Int = 0

func pathSum(_ root: TreeNode?, _ sum: Int) -> Int {
cnt[0] = 1
target = sum
return dfs(root, 0)
var cnt: [Int: Int] = [0: 1]

}
func dfs(_ root: TreeNode?, _ s: Int) -> Int {
guard let root = root else { return 0 }

private func dfs(_ root: TreeNode?, _ s: Int) -> Int {
guard let root = root else {
return 0
}
let newSum = s + root.val
let ans = cnt[newSum - target, default: 0]
var s = s + root.val
var ans = cnt[s - sum, default: 0]

cnt[newSum, default: 0] += 1
let leftPaths = dfs(root.left, newSum)
let rightPaths = dfs(root.right, newSum)
cnt[newSum, default: 0] -= 1
cnt[s, default: 0] += 1
ans += dfs(root.left, s)
ans += dfs(root.right, s)
cnt[s, default: 0] -= 1

return ans + leftPaths + rightPaths
return ans
}

return dfs(root, 0)
}
}
```
Expand Down
79 changes: 37 additions & 42 deletions lcci/04.12.Paths with Sum/README_EN.md
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Expand Up @@ -83,15 +83,13 @@ The time complexity is $O(n)$, and the space complexity is $O(n)$. Here, $n$ is
```python
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None


# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def pathSum(self, root: TreeNode, sum: int) -> int:
def dfs(root: TreeNode, s: int):
def pathSum(self, root: Optional[TreeNode], sum: int) -> int:
def dfs(root: Optional[TreeNode], s: int) -> int:
if root is None:
return 0
s += root.val
Expand Down Expand Up @@ -158,9 +156,8 @@ class Solution {
class Solution {
public:
int pathSum(TreeNode* root, int sum) {
unordered_map<long long, int> cnt;
cnt[0] = 1;
function<int(TreeNode*, long long)> dfs = [&](TreeNode* root, long long s) {
unordered_map<long long, int> cnt{{0, 1}};
auto dfs = [&](this auto&& dfs, TreeNode* root, long long s) -> int {
if (!root) {
return 0;
}
Expand Down Expand Up @@ -298,42 +295,40 @@ impl Solution {
#### Swift

```swift
/* class TreeNode {
* var val: Int
* var left: TreeNode?
* var right: TreeNode?
*
* init(_ val: Int, _ left: TreeNode? = nil, _ right: TreeNode? = nil) {
* self.val = val
* self.left = left
* self.right = right
* }
* }
*/

/**
* Definition for a binary tree node.
* public class TreeNode {
* public var val: Int
* public var left: TreeNode?
* public var right: TreeNode?
* public init() { self.val = 0; self.left = nil; self.right = nil; }
* public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
* public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
* self.val = val
* self.left = left
* self.right = right
* }
* }
*/
class Solution {
private var cnt: [Int: Int] = [:]
private var target: Int = 0

func pathSum(_ root: TreeNode?, _ sum: Int) -> Int {
cnt[0] = 1
target = sum
return dfs(root, 0)
}
var cnt: [Int: Int] = [0: 1]

private func dfs(_ root: TreeNode?, _ s: Int) -> Int {
guard let root = root else {
return 0
}
let newSum = s + root.val
let ans = cnt[newSum - target, default: 0]
func dfs(_ root: TreeNode?, _ s: Int) -> Int {
guard let root = root else { return 0 }

var s = s + root.val
var ans = cnt[s - sum, default: 0]

cnt[s, default: 0] += 1
ans += dfs(root.left, s)
ans += dfs(root.right, s)
cnt[s, default: 0] -= 1

cnt[newSum, default: 0] += 1
let leftPaths = dfs(root.left, newSum)
let rightPaths = dfs(root.right, newSum)
cnt[newSum, default: 0] -= 1
return ans
}

return ans + leftPaths + rightPaths
return dfs(root, 0)
}
}
```
Expand Down
7 changes: 3 additions & 4 deletions lcci/04.12.Paths with Sum/Solution.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -10,9 +10,8 @@
class Solution {
public:
int pathSum(TreeNode* root, int sum) {
unordered_map<long long, int> cnt;
cnt[0] = 1;
function<int(TreeNode*, long long)> dfs = [&](TreeNode* root, long long s) {
unordered_map<long long, int> cnt{{0, 1}};
auto dfs = [&](this auto&& dfs, TreeNode* root, long long s) -> int {
if (!root) {
return 0;
}
Expand All @@ -26,4 +25,4 @@ class Solution {
};
return dfs(root, 0);
}
};
};
14 changes: 6 additions & 8 deletions lcci/04.12.Paths with Sum/Solution.py
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Original file line number Diff line number Diff line change
@@ -1,14 +1,12 @@
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None


# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def pathSum(self, root: TreeNode, sum: int) -> int:
def dfs(root: TreeNode, s: int):
def pathSum(self, root: Optional[TreeNode], sum: int) -> int:
def dfs(root: Optional[TreeNode], s: int) -> int:
if root is None:
return 0
s += root.val
Expand Down
64 changes: 31 additions & 33 deletions lcci/04.12.Paths with Sum/Solution.swift
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Original file line number Diff line number Diff line change
@@ -1,38 +1,36 @@
/* class TreeNode {
* var val: Int
* var left: TreeNode?
* var right: TreeNode?
*
* init(_ val: Int, _ left: TreeNode? = nil, _ right: TreeNode? = nil) {
* self.val = val
* self.left = left
* self.right = right
* }
* }
*/

/**
* Definition for a binary tree node.
* public class TreeNode {
* public var val: Int
* public var left: TreeNode?
* public var right: TreeNode?
* public init() { self.val = 0; self.left = nil; self.right = nil; }
* public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
* public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
* self.val = val
* self.left = left
* self.right = right
* }
* }
*/
class Solution {
private var cnt: [Int: Int] = [:]
private var target: Int = 0

func pathSum(_ root: TreeNode?, _ sum: Int) -> Int {
cnt[0] = 1
target = sum
return dfs(root, 0)
}
var cnt: [Int: Int] = [0: 1]

func dfs(_ root: TreeNode?, _ s: Int) -> Int {
guard let root = root else { return 0 }

private func dfs(_ root: TreeNode?, _ s: Int) -> Int {
guard let root = root else {
return 0
var s = s + root.val
var ans = cnt[s - sum, default: 0]

cnt[s, default: 0] += 1
ans += dfs(root.left, s)
ans += dfs(root.right, s)
cnt[s, default: 0] -= 1

return ans
}
let newSum = s + root.val
let ans = cnt[newSum - target, default: 0]

cnt[newSum, default: 0] += 1
let leftPaths = dfs(root.left, newSum)
let rightPaths = dfs(root.right, newSum)
cnt[newSum, default: 0] -= 1

return ans + leftPaths + rightPaths

return dfs(root, 0)
}
}
}
8 changes: 4 additions & 4 deletions lcci/05.03.Reverse Bits/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -134,13 +134,13 @@ function reverseBits(num: number): number {
class Solution {
func reverseBits(_ num: Int) -> Int {
var ans = 0
var countZeros = 0
var cnt = 0
var j = 0

for i in 0..<32 {
countZeros += (num >> i & 1 ^ 1)
while countZeros > 1 {
countZeros -= (num >> j & 1 ^ 1)
cnt += (num >> i & 1 ^ 1)
while cnt > 1 {
cnt -= (num >> j & 1 ^ 1)
j += 1
}
ans = max(ans, i - j + 1)
Expand Down
8 changes: 4 additions & 4 deletions lcci/05.03.Reverse Bits/README_EN.md
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Expand Up @@ -142,13 +142,13 @@ function reverseBits(num: number): number {
class Solution {
func reverseBits(_ num: Int) -> Int {
var ans = 0
var countZeros = 0
var cnt = 0
var j = 0

for i in 0..<32 {
countZeros += (num >> i & 1 ^ 1)
while countZeros > 1 {
countZeros -= (num >> j & 1 ^ 1)
cnt += (num >> i & 1 ^ 1)
while cnt > 1 {
cnt -= (num >> j & 1 ^ 1)
j += 1
}
ans = max(ans, i - j + 1)
Expand Down
8 changes: 4 additions & 4 deletions lcci/05.03.Reverse Bits/Solution.swift
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Original file line number Diff line number Diff line change
@@ -1,13 +1,13 @@
class Solution {
func reverseBits(_ num: Int) -> Int {
var ans = 0
var countZeros = 0
var cnt = 0
var j = 0

for i in 0..<32 {
countZeros += (num >> i & 1 ^ 1)
while countZeros > 1 {
countZeros -= (num >> j & 1 ^ 1)
cnt += (num >> i & 1 ^ 1)
while cnt > 1 {
cnt -= (num >> j & 1 ^ 1)
j += 1
}
ans = max(ans, i - j + 1)
Expand Down
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