[DP] Add a solution to Can I Win

Author: soapyigu

DP/CanIWin.swift

@@ -0,0 +1,41 @@
+/**
+ * Question Link: https://leetcode.com/problems/can-i-win/
+ * Primary idea: Dynamic Programming, use current and bit manipulation to track cases
+ * Time Complexity: O(2^n), Space Complexity: O(n)
+ *
+ */
+
+ class CanIWin {
+    func canIWin(_ maxChoosableInteger: Int, _ desiredTotal: Int) -> Bool {
+        if maxChoosableInteger >= desiredTotal {
+            return true
+        }
+        if (maxChoosableInteger + 1) * maxChoosableInteger / 2 < desiredTotal {
+            return false
+        }
+        
+        var memo = [Int: Bool]()
+        return helper(maxChoosableInteger, desiredTotal, 0, &memo)
+    }
+    
+    fileprivate func helper(_ maxChoosableInteger: Int, _ desiredTotal: Int, _ used: Int, _ memo: inout [Int: Bool]) -> Bool {
+        if let canWin = memo[used] {
+            return canWin
+        }
+        
+        for i in 0..<maxChoosableInteger {
+            let current = 1 << i
+            
+            if current & used == 0 {
+                if desiredTotal <= i + 1 || !helper(maxChoosableInteger, desiredTotal - i - 1, current | used, &memo) {
+                    memo[used] = true
+                    return true
+                }
+            }
+            
+        }
+        
+        memo[used] = false
+        return false
+    }
+}

DP/Triangle.swift

@@ -1,7 +1,7 @@
 /**
  * Question Link: https://leetcode.com/problems/triangle/
  * Primary idea: Dynamic Programming, start from bottom to top
- * Time Complexity: O(2^n - 1), Space Complexity: O(m)
+ * Time Complexity: O(2^n), Space Complexity: O(m)
  *
  */
 

README.md

@@ -28,7 +28,7 @@
 * [Microsoft](#microsoft)
 
 ## Progress
-[Problem Status](#problem-status) shows the latest progress to all 800+ questions. Currently we have 241 completed solutions. Note: questions with ♥ mark means that you have to **Subscript to premium membership** of LeetCode to unlock them. Thank you for great contributions from [CharleneJiang](https://github.com/CharleneJiang), [ReadmeCritic](https://github.com/ReadmeCritic), [demonkoo](https://github.com/demonkoo), [DaiYue](https://github.com/DaiYue), [Quaggie](https://github.com/Quaggie) and [jindulys](https://github.com/jindulys).
+[Problem Status](#problem-status) shows the latest progress to all 800+ questions. Currently we have 242 completed solutions. Note: questions with ♥ mark means that you have to **Subscript to premium membership** of LeetCode to unlock them. Thank you for great contributions from [CharleneJiang](https://github.com/CharleneJiang), [ReadmeCritic](https://github.com/ReadmeCritic), [demonkoo](https://github.com/demonkoo), [DaiYue](https://github.com/DaiYue), [Quaggie](https://github.com/Quaggie) and [jindulys](https://github.com/jindulys).
 
 
 ## Array
@@ -175,6 +175,7 @@
 [Unique Paths](https://leetcode.com/problems/unique-paths/)| [Swift](./DP/UniquePaths.swift)| Medium| O(mn)| O(mn)|
 [Unique Paths II](https://leetcode.com/problems/unique-paths-ii/)| [Swift](./DP/UniquePathsII.swift)| Medium| O(mn)| O(mn)|
 [Flip Game II](https://leetcode.com/problems/flip-game-ii/)| [Swift](./DP/FlipGameII.swift)| Medium| O(n)| O(n)|
+[Can I Win](https://leetcode.com/problems/can-i-win/)| [Swift](./DP/CanIWin.swift)| Medium| O(2^n)| O(n)|
 [Decode Ways](https://leetcode.com/problems/decode-ways/)| [Swift](./DP/DecodeWays.swift) | O(n)|O(n)|
 [Minimum Path Sum](https://leetcode.com/problems/minimum-path-sum/)| [Swift](./DP/MinimumPathSum.swift)| Medium| O(mn)| O(mn)|
 [Generate Parentheses](https://leetcode.com/problems/generate-parentheses/)| [Swift](./DP/GenerateParentheses.swift)| Medium| O(2^n)| O(n)|
@@ -184,7 +185,7 @@
 [Best Time to Buy and Sell Stock III](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/)| [Swift](./DP/BestTimeBuySellStockIII.swift)| Hard| O(n)| O(n)|
 [Best Time to Buy and Sell Stock IV](https://leetcode.com/problems/https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv/)| [Swift](./DP/BestTimeBuySellStockIV.swift)| Hard| O(n^2)| O(n)|
 [Best Time to Buy and Sell Stock with Cooldown](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown/)| [Swift](./DP/BestTimeBuySellStockCooldown.swift)| Medium| O(n^2)| O(n)|
-[Maximum Sum of 3 Non-Overlapping Subarrays](https://leetcode.com/problems/maximum-sum-of-3-non-overlapping-subarrays/)| [Swift](./DP/MaximumSumThreeNonOverlappingSubarrays.swift| O(n)| O(n)|
+[Maximum Sum of 3 Non-Overlapping Subarrays](https://leetcode.com/problems/maximum-sum-of-3-non-overlapping-subarrays/)| [Swift](./DP/MaximumSumThreeNonOverlappingSubarrays.swift| Hard| O(n)| O(n)|
 [Coin Change](https://leetcode.com/problems/coin-change/)| [Swift](./DP/CoinChange.swift)| Medium| O(n^2)| O(n)|
 [Coin Change II](https://leetcode.com/problems/coin-change-ii/)| [Swift](./DP/CoinChangeII.swift)| Medium| O(n^2)| O(n)|
 [Longest Increasing Subsequence](https://leetcode.com/problems/longest-increasing-subsequence/)| [Swift](./DP/LongestIncreasingSubsequence.swift)| Medium| O(n^2)| O(n)|
@@ -198,7 +199,7 @@
 [Maximal Square](https://leetcode.com/problems/maximal-square/)| [Swift](./DP/MaximalSquare.swift)| Medium| O(mn)| O(mn)|
 [Edit Distance](https://leetcode.com/problems/edit-distance/)| [Swift](./DP/EditDistance.swift)| Hard| O(mn)| O(mn)|
 [Combination Sum IV](https://leetcode.com/problems/combination-sum-iv/)| [Swift](./DP/CombinationSumIV.swift)| Medium| O(2^n)| O(n)|
-[Triangle](https://leetcode.com/problems/triangle/)| [Swift](./DP/Triangle.swift)| Medium| O(2^n - 1)| O(m)|
+[Triangle](https://leetcode.com/problems/triangle/)| [Swift](./DP/Triangle.swift)| Medium| O(2^n)| O(m)|
 [Wildcard Matching](https://leetcode.com/problems/wildcard-matching/)| [Swift](./DP/WildcardMatching.swift)| Hard| O(mn)| O(mn)|
 [Regular Expression Matching](https://leetcode.com/problems/regular-expression-matching/)| [Swift](./DP/RegularExpressionMatching.swift)| Hard| O(mn)| O(mn)|
 [Minimum Window Subsequence](https://leetcode.com/problems/minimum-window-subsequence/)| [Swift](./DP/MinimumWindowSubsequence.swift)| Hard| O(mn)| O(mn)|