Merge remote-tracking branch 'origin/master'

Author: kkarpyshev

src/easy/942. DI String Match .kt

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+package easy
+
+import ArraysTopic
+import GreedyTopic
+import MathTopic
+import StringTopic
+import TwoPointersTopic
+
+/**
+ * 942. DI String Match
+ * https://leetcode.com/problems/length-of-last-word/
+ *
+ * Given a string s consisting of some words separated by some number of spaces, return the length of the last word in the string.
+ * A word is a maximal substring consisting of non-space characters only.
+ */
+
+class Easy942 : ArraysTopic, TwoPointersTopic, StringTopic, GreedyTopic, MathTopic {
+
+    fun diStringMatch(s: String): IntArray {
+        val result = IntArray(s.length + 1)
+        var top = 0
+        var bottom = 0
+        for (i in result.lastIndex - 1 downTo 0) {
+            if (s[i] == 'I') {
+                bottom--
+                result[i] = bottom
+            } else {
+                top++
+                result[i] = top
+            }
+        }
+        return result.also { for (i in it.indices) it[i] -= bottom }
+    }
+}
+
+fun main() {
+    println(Easy942().diStringMatch("IDID").toList())
+    println(Easy942().diStringMatch("III").toList())
+    println(Easy942().diStringMatch("DDI").toList())
+}

src/medium/881. Boats to Save People .kt

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+package medium
+
+import ArraysTopic
+import GreedyTopic
+import SortingTopic
+import TwoPointersTopic
+
+/**
+ * 881. Boats to Save People
+ * https://leetcode.com/problems/boats-to-save-people/
+ *
+You are given an array people where people[i] is the weight of the ith person,
+and an infinite number of boats where each boat can carry a maximum weight of limit.
+Each boat carries at most two people at the same time, provided the sum of the weight of those people is at most limit.
+Return the minimum number of boats to carry every given person.
+ */
+
+class Medium881 : ArraysTopic, TwoPointersTopic, GreedyTopic, SortingTopic {
+
+    fun numRescueBoats(people: IntArray, limit: Int): Int {
+        people.sort()
+        var result = 0
+        for (i in people.indices) {
+            if (people[i] == 0) continue
+            for (j in people.lastIndex downTo i + 1) {
+                if (people[j] == 0) continue
+                if (people[j] + people[i] > limit) continue
+                people[j] = 0
+                break
+            }
+            people[i] = 0
+            result++
+        }
+        return result
+    }
+}
+
+fun main() {
+    println(Medium881().numRescueBoats(intArrayOf(1, 2), 3))
+    println(Medium881().numRescueBoats(intArrayOf(3, 2, 2, 1), 3))
+    println(Medium881().numRescueBoats(intArrayOf(3, 5, 3, 4), 5))
+    println(Medium881().numRescueBoats(intArrayOf(5, 1, 4, 2), 6))
+}

src/medium/991. Broken Calculator .kt

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+package medium
+
+import GreedyTopic
+import MathTopic
+
+
+/**
+ * 991. Broken Calculator
+ * https://leetcode.com/problems/broken-calculator/
+ *
+There is a broken calculator that has the integer startValue on its display initially. In one operation, you can:
+multiply the number on display by 2, or
+subtract 1 from the number on display.
+Given two integers startValue and target, return the minimum number of operations needed to display target on the calculator.
+ BULLSHIT
+ */
+
+class Medium991 : MathTopic, GreedyTopic {
+
+    fun brokenCalc(startValue: Int, target: Int): Int {
+        var value = target
+        var ans = 0
+        while (value > startValue) {
+            ans++
+            value = if (value % 2 == 1) value + 1 else value / 2
+        }
+        return ans + startValue - value
+    }
+}
+
+fun main() {
+    println(Medium991().brokenCalc(2, 3))
+    println(Medium991().brokenCalc(5, 8))
+    println(Medium991().brokenCalc(3, 10))
+}