Commit 426f993

authored

feat: add swift implementation to lcci problem: No.04.12 (doocs#2662)

1 parent ca67b79 commit 426f993Copy full SHA for 426f993

File tree

+121

-0

lines changed

+121

-0

lines changed

Lines changed: 42 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -257,6 +257,48 @@ impl Solution {`
`257`	`257`	`}`
`258`	`258`	```
`259`	`259`
	`260`	+```swift
	`261`	`+/* class TreeNode {`
	`262`	`+* var val: Int`
	`263`	`+* var left: TreeNode?`
	`264`	`+* var right: TreeNode?`
	`265`	`+*`
	`266`	`+* init(_ val: Int, _ left: TreeNode? = nil, _ right: TreeNode? = nil) {`
	`267`	`+* self.val = val`
	`268`	`+* self.left = left`
	`269`	`+* self.right = right`
	`270`	`+* }`
	`271`	`+* }`
	`272`	`+*/`
	`273`	`+`
	`274`	`+class Solution {`
	`275`	`+ private var cnt: [Int: Int] = [:]`
	`276`	`+ private var target: Int = 0`
	`277`	`+`
	`278`	`+ func pathSum(_ root: TreeNode?, _ sum: Int) -> Int {`
	`279`	`+ cnt[0] = 1`
	`280`	`+ target = sum`
	`281`	`+ return dfs(root, 0)`
	`282`	`+`
	`283`	`+ }`
	`284`	`+`
	`285`	`+ private func dfs(_ root: TreeNode?, _ s: Int) -> Int {`
	`286`	`+ guard let root = root else {`
	`287`	`+ return 0`
	`288`	`+ }`
	`289`	`+ let newSum = s + root.val`
	`290`	`+ let ans = cnt[newSum - target, default: 0]`
	`291`	`+`
	`292`	`+ cnt[newSum, default: 0] += 1`
	`293`	`+ let leftPaths = dfs(root.left, newSum)`
	`294`	`+ let rightPaths = dfs(root.right, newSum)`
	`295`	`+ cnt[newSum, default: 0] -= 1`
	`296`	`+`
	`297`	`+ return ans + leftPaths + rightPaths`
	`298`	`+ }`
	`299`	`+}`
	`300`	+```
	`301`	`+`
`260`	`302`	`<!-- tabs:end -->`
`261`	`303`
`262`	`304`	`<!-- end -->`

Lines changed: 41 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -269,6 +269,47 @@ impl Solution {`
`269`	`269`	`}`
`270`	`270`	```
`271`	`271`
	`272`	+```swift
	`273`	`+/* class TreeNode {`
	`274`	`+* var val: Int`
	`275`	`+* var left: TreeNode?`
	`276`	`+* var right: TreeNode?`
	`277`	`+*`
	`278`	`+* init(_ val: Int, _ left: TreeNode? = nil, _ right: TreeNode? = nil) {`
	`279`	`+* self.val = val`
	`280`	`+* self.left = left`
	`281`	`+* self.right = right`
	`282`	`+* }`
	`283`	`+* }`
	`284`	`+*/`
	`285`	`+`
	`286`	`+class Solution {`
	`287`	`+ private var cnt: [Int: Int] = [:]`
	`288`	`+ private var target: Int = 0`
	`289`	`+`
	`290`	`+ func pathSum(_ root: TreeNode?, _ sum: Int) -> Int {`
	`291`	`+ cnt[0] = 1`
	`292`	`+ target = sum`
	`293`	`+ return dfs(root, 0)`
	`294`	`+ }`
	`295`	`+`
	`296`	`+ private func dfs(_ root: TreeNode?, _ s: Int) -> Int {`
	`297`	`+ guard let root = root else {`
	`298`	`+ return 0`
	`299`	`+ }`
	`300`	`+ let newSum = s + root.val`
	`301`	`+ let ans = cnt[newSum - target, default: 0]`
	`302`	`+`
	`303`	`+ cnt[newSum, default: 0] += 1`
	`304`	`+ let leftPaths = dfs(root.left, newSum)`
	`305`	`+ let rightPaths = dfs(root.right, newSum)`
	`306`	`+ cnt[newSum, default: 0] -= 1`
	`307`	`+`
	`308`	`+ return ans + leftPaths + rightPaths`
	`309`	`+ }`
	`310`	`+}`
	`311`	+```
	`312`	`+`
`272`	`313`	`<!-- tabs:end -->`
`273`	`314`
`274`	`315`	`<!-- end -->`

Lines changed: 38 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,38 @@`
	`1`	`+/* class TreeNode {`
	`2`	`+* var val: Int`
	`3`	`+* var left: TreeNode?`
	`4`	`+* var right: TreeNode?`
	`5`	`+*`
	`6`	`+* init(_ val: Int, _ left: TreeNode? = nil, _ right: TreeNode? = nil) {`
	`7`	`+* self.val = val`
	`8`	`+* self.left = left`
	`9`	`+* self.right = right`
	`10`	`+* }`
	`11`	`+* }`
	`12`	`+*/`
	`13`	`+`
	`14`	`+class Solution {`
	`15`	`+ private var cnt: [Int: Int] = [:]`
	`16`	`+ private var target: Int = 0`
	`17`	`+`
	`18`	`+ func pathSum(_ root: TreeNode?, _ sum: Int) -> Int {`
	`19`	`+ cnt[0] = 1`
	`20`	`+ target = sum`
	`21`	`+ return dfs(root, 0)`
	`22`	`+ }`
	`23`	`+`
	`24`	`+ private func dfs(_ root: TreeNode?, _ s: Int) -> Int {`
	`25`	`+ guard let root = root else {`
	`26`	`+ return 0`
	`27`	`+ }`
	`28`	`+ let newSum = s + root.val`
	`29`	`+ let ans = cnt[newSum - target, default: 0]`
	`30`	`+`
	`31`	`+ cnt[newSum, default: 0] += 1`
	`32`	`+ let leftPaths = dfs(root.left, newSum)`
	`33`	`+ let rightPaths = dfs(root.right, newSum)`
	`34`	`+ cnt[newSum, default: 0] -= 1`
	`35`	`+`
	`36`	`+ return ans + leftPaths + rightPaths`
	`37`	`+ }`
	`38`	`+}`

Comments

(0)