Add 338 Counting Bits

Author: jindulys

LeetcodeSwift.xcodeproj/project.pbxproj

@@ -24,6 +24,7 @@
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 		0E68967A1DD787E6006F10D3 /* QuickMedianTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0E6896791DD787E6006F10D3 /* QuickMedianTest.swift */; };
 		0E68967C1DD79478006F10D3 /* 223_RectangleArea.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0E68967B1DD79478006F10D3 /* 223_RectangleArea.swift */; };
+		0E68967E1DD7A57A006F10D3 /* 338_CountingBits.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0E68967D1DD7A57A006F10D3 /* 338_CountingBits.swift */; };
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@@ -144,6 +145,7 @@
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 		0E6896791DD787E6006F10D3 /* QuickMedianTest.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = QuickMedianTest.swift; sourceTree = "<group>"; };
 		0E68967B1DD79478006F10D3 /* 223_RectangleArea.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = 223_RectangleArea.swift; sourceTree = "<group>"; };
+		0E68967D1DD7A57A006F10D3 /* 338_CountingBits.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = 338_CountingBits.swift; sourceTree = "<group>"; };
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 		0E6CDE821D98BA4100FB662F /* ArrayExtensionTest.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ArrayExtensionTest.swift; sourceTree = "<group>"; };
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@@ -447,6 +449,7 @@
 				0EB7AD5F1D7E273A00278C48 /* 258_AddDigits.swift */,
 				0EB7AD6D1D7E5CB500278C48 /* 263_UglyNumber.swift */,
 				0EB7AD691D7E4C7D00278C48 /* 326_PowerOfThree.swift */,
+				0E68967D1DD7A57A006F10D3 /* 338_CountingBits.swift */,
 			);
 			path = Math;
 			sourceTree = "<group>";
@@ -620,6 +623,7 @@
 				0E5D155B1D7FBB7C001EB24C /* 8_StringToInteger.swift in Sources */,
 				0E7D77D81DCE815C006DD938 /* 49_GroupAnagrams.swift in Sources */,
 				0EE265231DD416E400D2B0B1 /* 23_MergeKSortedLists.swift in Sources */,
+				0E68967E1DD7A57A006F10D3 /* 338_CountingBits.swift in Sources */,
 				0E6FADCB1D58172200C8D71D /* 113_PathSumII.swift in Sources */,
 				0E6FADB11D58171900C8D71D /* 290_WordPattern.swift in Sources */,
 				0E6FADCA1D58172200C8D71D /* 112_PathSum.swift in Sources */,

Sources/Math/338_CountingBits.swift

@@ -0,0 +1,35 @@
+//
+//  338_CountingBits.swift
+//  LeetcodeSwift
+//
+//  Created by yansong li on 2016-11-12.
+//  Copyright © 2016 YANSONG LI. All rights reserved.
+//
+
+import Foundation
+
+/**
+	Title:338 Counting Bits
+	URL: https://leetcode.com/problems/counting-bits/
+	Space: O(N)
+	Time: O(N)
+ */
+
+class CountingBits_Solution {
+  func countBits(_ num: Int) -> [Int] {
+    guard num > 0 else {
+      return [0]
+    }
+    var result = Array(repeating: 0, count: num + 1)
+    var x = 1
+    for i in 1...num {
+      if i == x {
+        x = x << 1
+        result[i] = 1
+      } else {
+        result[i] = result[i - (x >> 1)] + 1
+      }
+    }
+    return result
+  }
+}