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Commit 25c659e

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author
kkarpyshev
committed
Merge remote-tracking branch 'origin/master'
2 parents 8db9190 + 1286cde commit 25c659e

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4 files changed

+146
-1
lines changed

4 files changed

+146
-1
lines changed

‎src/medium/138. Copy List with Random Pointer .kt‎

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@@ -22,7 +22,7 @@ import LinkedListTopic
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* Your code will only be given the head of the original linked list.
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*/
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class Medium138: HashTableTopic, LinkedListTopic {
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class Medium138: HashTableTopic, LinkedListTopic {
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fun copyRandomList(head: Node?): Node? {
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head ?: return null

‎src/medium/71. Simplify Path .kt‎

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package medium
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import StackTopic
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import StringTopic
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import java.util.*
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/**
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* 71. Simplify Path
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* https://leetcode.com/problems/simplify-path/
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*
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Given a string path, which is an absolute path (starting with a slash '/') to a file or directory in a Unix-style file system, convert it to the simplified canonical path.
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In a Unix-style file system, a period '.' refers to the current directory, a double period '..' refers to the directory up a level, and any multiple consecutive slashes (i.e. '//') are treated as a single slash '/'. For this problem, any other format of periods such as '...' are treated as file/directory names.
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The canonical path should have the following format:
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The path starts with a single slash '/'.
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Any two directories are separated by a single slash '/'.
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The path does not end with a trailing '/'.
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The path only contains the directories on the path from the root directory to the target file or directory (i.e., no period '.' or double period '..')
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Return the simplified canonical path.
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*/
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class Medium71 : StringTopic, StackTopic {
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fun simplifyPath(path: String): String {
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val stack = Stack<String>()
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var start = -1
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for (i in 0..path.length) {
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if (i == path.length || path[i] == '/') {
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if (start > 0) {
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when (val dir = path.substring(start, i)) {
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"." -> Unit
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".." -> if (stack.isNotEmpty()) stack.pop()
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else -> stack.add(dir)
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}
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start = -1
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}
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} else {
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if (start < 0) start = i
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}
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}
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return stack.joinToString("/", "/")
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}
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}
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fun main() {
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println(Medium71().simplifyPath("/home/")) // /home
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println(Medium71().simplifyPath("/../")) // /
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println(Medium71().simplifyPath("/home//foo/")) // /home/foo
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println(Medium71().simplifyPath("/a/./b/../../c/")) // /c
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println(Medium71().simplifyPath("/...")) // /
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}
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package medium
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import StackTopic
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import StringTopic
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import java.util.*
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/**
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* 856. Score of Parentheses
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* https://leetcode.com/problems/score-of-parentheses/
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*
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Given a balanced parentheses string s, return the score of the string.
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The score of a balanced parentheses string is based on the following rule:
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"()" has score 1.
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AB has score A + B, where A and B are balanced parentheses strings.
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(A) has score 2 * A, where A is a balanced parentheses string.
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BULLSHIT
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*/
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class Medium856 : StringTopic, StackTopic {
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fun scoreOfParentheses(s: String): Int {
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val stack = Stack<Int>()
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stack.push(0)
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for (i in s.indices) {
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if (s[i] == '(') {
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stack.push(0)
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} else {
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val v = stack.pop()
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val w = stack.pop()
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stack.push(w + maxOf(2 * v, 1))
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}
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}
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return stack.pop()
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}
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}
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fun main() {
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println(Medium856().scoreOfParentheses("()"))
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println(Medium856().scoreOfParentheses("(())"))
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println(Medium856().scoreOfParentheses("()()"))
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println(Medium856().scoreOfParentheses("(()(()))"))
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}
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package medium
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import ArraysTopic
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import StackTopic
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import java.util.*
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/**
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* 946. Validate Stack Sequences
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* https://leetcode.com/problems/validate-stack-sequences/
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*
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Given two integer arrays pushed and popped each with distinct values,
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return true if this could have been the result of a sequence of push and pop operations on an initially empty stack, or false otherwise.
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*/
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class Medium946 : ArraysTopic, StackTopic {
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fun validateStackSequences(pushed: IntArray, popped: IntArray): Boolean {
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val stack = Stack<Int>()
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var i = 0
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var j = 0
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while (i < pushed.size || j < popped.size) {
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if (stack.isEmpty()) {
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if (i < pushed.size) {
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stack.push(pushed[i])
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i++
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} else return false
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} else {
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if (j < popped.size) {
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if (popped[j] == stack.peek()) {
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stack.pop()
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j++
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} else {
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if (i < pushed.size) {
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stack.push(pushed[i])
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i++
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} else return false
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}
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} else return false
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}
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}
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return true
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}
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}
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fun main() {
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println(Medium946().validateStackSequences(intArrayOf(1, 2, 3, 4, 5), intArrayOf(4, 5, 3, 2, 1)))
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println(Medium946().validateStackSequences(intArrayOf(1, 2, 3, 4, 5), intArrayOf(4, 3, 5, 1, 2)))
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}

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