Base 7.

Author: recherst

Easy/476.Number Complement.playground/xcuserdata/recherst.xcuserdatad/xcschemes/xcschememanagement.plist

@@ -0,0 +1,16 @@
+<?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>SchemeUserState</key>
+	<dict>
+		<key>476.Number Complement (Playground).xcscheme</key>
+		<dict>
+			<key>isShown</key>
+			<false/>
+			<key>orderHint</key>
+			<integer>0</integer>
+		</dict>
+	</dict>
+</dict>
+</plist>

Easy/485.Max Consecutive Ones.playground/xcuserdata/recherst.xcuserdatad/xcschemes/xcschememanagement.plist

@@ -0,0 +1,16 @@
+<?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>SchemeUserState</key>
+	<dict>
+		<key>485.Max Consecutive Ones (Playground).xcscheme</key>
+		<dict>
+			<key>isShown</key>
+			<false/>
+			<key>orderHint</key>
+			<integer>0</integer>
+		</dict>
+	</dict>
+</dict>
+</plist>

Easy/504.Base 7.playground/Contents.swift

@@ -0,0 +1,60 @@
+/**
+ Given an integer num, return a string of its base 7 representation.
+
+  
+
+ Example 1:
+ Input: num = 100
+ Output: "202"
+ 
+ Example 2:
+ Input: num = -7
+ Output: "-10"
+  
+
+ Constraints:
+ - -107 <= num <= 107
+
+ */
+class Solution {
+    func convertToBase7(_ num: Int) -> String {
+        if num == 0 { return "0" }
+        var x = 0
+        while pow(7, x) <= abs(num) {
+            x += 1
+        }
+        x -= 1
+        let res = decimalToBinary(abs(num), maxBit: x)
+        return num > 0 ? res.lazy.reversed().map { String($0) }.joined() : "-" + res.lazy.reversed().map { String($0) }.joined()
+    }
+    
+    private func pow(_ base: Int, _ power: Int) -> Int {
+        if base == 0 { return 0 }
+        var res = 1
+        for _ in 0..<power {
+            res *= base
+        }
+        return res
+    }
+    
+    private func decimalToBinary(_ num: Int, maxBit bit: Int) -> [Int] {
+        var n = num
+        var i = bit
+        var arr = Array(repeating: 0, count: i + 1)
+        while i >= 0 && n > 0 {
+            var x = 1
+            while x * pow(7, i) <= n {
+                x += 1
+            }
+            x -= 1
+            n -= x * pow(7, i)
+            arr[i] = x
+            i -= 1
+        }
+        return arr
+    }
+}
+
+let s = Solution()
+let r = s.convertToBase7(100)
+print(r)

Easy/504.Base 7.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

Easy/504.Base 7.playground/playground.xcworkspace/contents.xcworkspacedata

@@ -101,6 +101,7 @@
 97. [Teemo Attacking](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/495.Teemo%20Attacking.playground/Contents.swift)
 98. [Next Greater Element I](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/496.Next%20Greater%20Element%20I.playground/Contents.swift)
 99. [Keyboard Row](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/500.Keyboard%20Row.playground/Contents.swift)
+100. [Base 7](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/501.Base%207.playground/Contents.swift)
 
 #### Medium