increase four solvtions

Author: EternalChildren

judgeSquareSum/judgeSquareSum.playground/Contents.swift

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+// Given a non-negative integer c, your task is to decide whether there're two integers a and b such that a2 + b2 = c.
+
+let num = 4
+
+// 264ms
+func judgeSquareSum(_ c: Int) -> Bool {
+    var hash = [Int: Int]()
+    var i = 0
+    var s = 0
+    while s <= c {
+        if s*2 == c || hash[c - s] != nil {
+            return true
+        } else {
+            hash[s] = 1
+            i += 1
+            s = i*i
+        }
+    }
+    return false
+}
+
+judgeSquareSum(num)

judgeSquareSum/judgeSquareSum.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='macos' executeOnSourceChanges='false'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

maxIncreaseKeepingSkyline/maxIncreaseKeepingSkyline.playground/Contents.swift

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+// In a 2 dimensional array grid, each value grid[i][j] represents the height of a building located there. We are allowed to increase the height of any number of buildings, by any amount (the amounts can be different for different buildings). Height 0 is considered to be a building as well.
+
+// At the end, the "skyline" when viewed from all four directions of the grid, i.e. top, bottom, left, and right, must be the same as the skyline of the original grid. A city's skyline is the outer contour of the rectangles formed by all the buildings when viewed from a distance. See the following example.
+
+// What is the maximum total sum that the height of the buildings can be increased?
+
+let nums = [[3,0,8,4],[2,4,5,7],[9,2,6,3],[0,3,1,0]]
+
+// 56ms
+func maxIncreaseKeepingSkyline(_ grid: [[Int]]) -> Int {
+    var tb = [Int]()
+    var lr = [Int]()
+    for i in grid {
+        lr.append(i.max()!)
+        if tb.count > 0 {
+            for index in 0..<i.count {
+                if i[index] > tb[index] {
+                    tb[index] = i[index]
+                }
+            }
+        }else{
+            tb = i
+        }
+    }
+    var res = 0
+    for i in 0..<grid.count {
+        for j in 0..<grid[i].count {
+            let max = lr[i] <= tb[j] ? lr[i] : tb[j]
+            res += max - grid[i][j]
+        }
+    }
+    return res
+}
+
+
+maxIncreaseKeepingSkyline(nums)

maxIncreaseKeepingSkyline/maxIncreaseKeepingSkyline.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='macos' executeOnSourceChanges='false'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

peakIndexInMountainArray/peakIndexInMountainArray.playground/Contents.swift

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+// Let's call an array A a mountain if the following properties hold:
+
+// A.length >= 3
+// There exists some 0 < i < A.length - 1 such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1]
+// Given an array that is definitely a mountain, return any i such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1].
+
+
+let nums = [0,2,1,0]
+
+
+// 96ms find the index for max
+func peakIndexInMountainArray(_ A: [Int]) -> Int {
+    return A.firstIndex(of: A.max()!)!
+}
+
+peakIndexInMountainArray(nums)

peakIndexInMountainArray/peakIndexInMountainArray.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='macos' executeOnSourceChanges='false'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

strWithout3a3b/strWithout3a3b.playground/Contents.swift

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+// Given two integers A and B, return any string S such that:
+
+// S has length A + B and contains exactly A 'a' letters, and exactly B 'b' letters;
+// The substring 'aaa' does not occur in S;
+// The substring 'bbb' does not occur in S.
+
+
+let A = 4
+let B = 8
+// 20ms
+func strWithout3a3b(_ A: Int, _ B: Int) -> String {
+    var str = ""
+    var A = A
+    var B = B
+    
+    while A > 0 || B > 0 {
+        var writeA = false
+        let count = str.count
+        if str.count >= 2 && str[str.index(before: str.endIndex)] == str[str.index(str.endIndex, offsetBy: -2)] {
+            if str[str.index(before: str.endIndex)] == "b" {
+                writeA = true
+            }
+        }else{
+            if A > B {
+                writeA = true
+            }
+        }
+        
+        if writeA {
+            A -= 1
+            str.append("a")
+        } else {
+            B -= 1
+            str.append("b")
+        }
+    }
+    return str
+}
+
+strWithout3a3b(A, B)
+

strWithout3a3b/strWithout3a3b.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='macos' executeOnSourceChanges='false'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

strWithout3a3b/strWithout3a3b.playground/playground.xcworkspace/contents.xcworkspacedata

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>