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Commit 676e17d

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committed
add 8, 23, 689, 1014, 1422 ans update 22 at swift
1 parent daf8f2a commit 676e17d

6 files changed

+215
-0
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/**
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* 8. String to Integer (atoi)
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* https://leetcode.com/problems/string-to-integer-atoi/
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**/
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import Foundation
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class Solution {
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func myAtoi(_ s: String) -> Int {
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var ans = 0, chars = Array(s.trimmingCharacters(in: .whitespacesAndNewlines)).map { String(0ドル) }
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var isNumberStarted = false, isMinus = false
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for ch in chars {
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if ch == "+" && !isNumberStarted {
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isNumberStarted = true
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} else if ch == "-" && !isNumberStarted {
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isMinus = true
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isNumberStarted = true
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} else if ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"].contains(ch) {
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isNumberStarted = true
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ans = ans * 10 + (Int(ch)! * (isMinus ? -1 : 1))
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} else {
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break
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}
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if ans > Int(Int32.max) { ans = Int(Int32.max); break}
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if ans < Int(Int32.min) { ans = Int(Int32.min); break}
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}
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return ans
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}
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}

‎swift/0022-generate-parentheses.swift‎

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return result
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}
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}
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class Solution2 {
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func generateParenthesis(_ n: Int) -> [String] {
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var stack: [(s: String, opened: Int)] = [("", 0)]
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while stack[0].s.count < n * 2 {
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var newStack: [(s: String, opened: Int)] = []
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for row in stack {
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if n * 2 - row.s.count - row.opened >= 2 {
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newStack.append( (row.s + "(", row.opened + 1) )
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}
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if row.opened > 0 {
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newStack.append( (row.s + ")", row.opened - 1) )
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}
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}
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stack = newStack
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}
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return stack.map { 0ドル.s }
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}
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}
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/**
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* 23. Merge k Sorted Lists
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* https://leetcode.com/problems/merge-k-sorted-lists/
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**/
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/**
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* Definition for singly-linked list.
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* public class ListNode {
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* public var val: Int
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* public var next: ListNode?
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* public init() { self.val = 0; self.next = nil; }
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* public init(_ val: Int) { self.val = val; self.next = nil; }
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* public init(_ val: Int, _ next: ListNode?) { self.val = val; self.next = next; }
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* }
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*/
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class Solution {
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func mergeKLists(_ lists: [ListNode?]) -> ListNode? {
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let head: ListNode? = ListNode()
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var cur: ListNode? = head, lists = lists
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while lists.count > 0 {
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while lists.count > 0 && lists[lists.count-1] == nil { lists.popLast() }
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if lists.isEmpty { break }
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var nextIndex: Int?, i = 0
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while i < lists.count {
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if lists[i] != nil {
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if nextIndex == nil || lists[i]!.val < lists[nextIndex!]!.val {
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nextIndex = i
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}
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}
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i += 1
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}
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cur!.next = lists[nextIndex!]
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cur = cur?.next
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lists[nextIndex!] = lists[nextIndex!]!.next
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}
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return head!.next
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}
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}
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/**
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* 689. Maximum Sum of 3 Non-Overlapping Subarrays
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* https://leetcode.com/problems/maximum-sum-of-3-non-overlapping-subarrays/
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**/
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class Solution {
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func maxSumOfThreeSubarrays(_ nums: [Int], _ k: Int) -> [Int] {
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var dp: [(sum: Int, ind: Int)] = []
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var l = 0, r = -1, sum = 0
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while r < nums.count-1 {
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r += 1
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sum += nums[r]
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if r - l + 1 > k {
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sum -= nums[l]
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l += 1
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}
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if r - l + 1 == k {
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dp.append( (sum: sum, ind: l) )
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}
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}
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var best_dp = [(left: Int?, right: Int?)](repeating: (nil, nil), count: dp.count)
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var best = 0
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for i in 0 ... dp.count-1 {
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best_dp[i].left = dp[i].sum > dp[best].sum ? i : best
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best = best_dp[i].left!
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}
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best = dp.count - 1
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for i in (0 ... dp.count-1).reversed() {
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best_dp[i].right = dp[i].sum >= dp[best].sum ? i : best
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best = best_dp[i].right!
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}
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var ans: [Int] = [], ans_sum = 0
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for i in k ... best_dp.count-k-1 {
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let s = dp[i].sum + dp[best_dp[i-k].left!].sum + dp[best_dp[i+k].right!].sum
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if s > ans_sum {
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ans_sum = s
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ans = [best_dp[i-k].left!, i, best_dp[i+k].right!]
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}
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}
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return ans
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}
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}
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/**
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* 1014. Best Sightseeing Pair
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* https://leetcode.com/problems/best-sightseeing-pair/
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**/
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class Solution {
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func maxScoreSightseeingPair(_ values: [Int]) -> Int {
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var ans = values[0] + values[1] - 1
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for i in 0 ..< values.count-1 {
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let isum = values[i] + i
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for j in i+1 ..< values.count {
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ans = max(ans, isum + values[j] - j)
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}
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}
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return ans
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}
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}
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class Solution2 {
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func maxScoreSightseeingPair(_ values: [Int]) -> Int {
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var ans = values[0] + values[1] - 1
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var pref_sums: [Int] = [ values[0] ]
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for i in 1 ..< values.count {
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pref_sums.append( max(pref_sums[i-1], values[i] + i) )
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}
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var post_sums: [Int] = [ values[values.count-1] - values.count + 1 ]
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for j in (0 ... values.count-2).reversed() {
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post_sums.append( max(post_sums[post_sums.count-1], values[j] - j) )
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}
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post_sums = post_sums.reversed()
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for i in 0 ..< values.count-1 {
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ans = max(ans, pref_sums[i] + post_sums[i+1])
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}
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return ans
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}
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}
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/**
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* 1422. Maximum Score After Splitting a String
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* https://leetcode.com/problems/maximum-score-after-splitting-a-string/
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**/
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class Solution {
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func maxScore(_ s: String) -> Int {
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let chars = Array(s).map { String(0ドル) }
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var zeros = 0, ones = chars.filter { 0ドル == "1" }.count
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var i = 0, ans = 0
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while i <= chars.count - 2 {
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if chars[i] == "0" {
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zeros += 1
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} else {
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ones -= 1
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}
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ans = max(ans, zeros + ones)
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i += 1
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}
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return ans
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}
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}

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