Merge pull request soapyigu#220 from zj9205/master

Add solution for soapyigu#55 Jump Game and soapyigu#57. Insert Interval

Author: soapyigu

DP/JumpGame.swift

@@ -0,0 +1,22 @@
+/**
+ * Question Link: https://leetcode.com/problems/jump-game/
+ * Primary idea: check each position with the previous farest step can reach. If i > last farest step, means cannot reach
+ * Time Complexity: O(n), Space Complexity: O(1)
+ *
+ */
+
+class JumpGame {
+    func canJump(_ nums: [Int]) -> Bool {
+        var max = 0
+        
+        for i in 0 ..< nums.count {
+            let farestStep = i + nums[i]
+            if i > max {
+                return false
+            }
+            max = max > farestStep ? max : farestStep
+        }
+        
+        return true
+    }
+}

README.md

@@ -211,6 +211,7 @@
 [Guess Number Higher or Lower II](https://leetcode.com/problems/guess-number-higher-or-lower-ii/)| [Swift](./DP/GuessNumberHigherOrLowerII.swift)| Medium| O(nlogn)| O(n^2)|
 [Burst Ballons](https://leetcode.com/problems/burst-balloons/)| [Swift](./DP/BurstBalloons.swift)| Hard| O(n^3)| O(n)|
 [Frog Jump](https://leetcode.com/problems/frog-jump/)| [Swift](./DP/FrogJump.swift)| Hard| O(n^2)| O(n)|
+[Jump Game](https://leetcode.com/problems/jump-game/)| [Swift](./DP/JumpGame.swift)| Medium| O(n)| O(1)|
 
 ## Depth-first search
 | Title | Solution | Difficulty | Time | Space |
@@ -312,6 +313,7 @@
 [Merge Intervals](https://leetcode.com/problems/merge-intervals/)| [Swift](./Sort/MergeIntervals.swift)| Hard| O(nlogn)| O(n)|
 [Alien Dictionary](https://leetcode.com/problems/alien-dictionary/)| [Swift](./Sort/AlienDictionary.swift)| Hard| O(nm)| O(nm)|
 [Array Partition I](https://leetcode.com/problems/array-partition-i/description/)| [Swift](./Sort/ArrayPartitionI.swift)|Easy| O(nlogn)| O(n)|
+[Insert Interval](https://leetcode.com/problems/insert-interval/description/)| [Swift](./Sort/InsertInterval.swift)|Hard| O(n)| O(1)|
 
 ## Union Find
 | Title | Solution | Difficulty | Time | Space |
@@ -752,9 +754,9 @@
 |		|	60	|	[Permutation Sequence](https://oj.leetcode.com/problems/permutation-sequence/)	| Medium	|
 |	[Swift](./Array/SpiralMatrixII.swift)	|	59	|	[Spiral Matrix II](https://oj.leetcode.com/problems/spiral-matrix-ii/)	| Medium	|
 |	[Swift](./String/LengthLastWord.swift)	|	58	|	[Length of Last Word](https://oj.leetcode.com/problems/length-of-last-word/)	| Easy	|
-|		|	57	|	[Insert Interval](https://oj.leetcode.com/problems/insert-interval/)	| Hard	|
+| [Swift](./Sort/InsertInterval.swift) |	57	|	[Insert Interval](https://oj.leetcode.com/problems/insert-interval/)	| Hard	|
 |	[Swift](./Sort/MergeIntervals.swift)	|	56	|	[Merge Intervals](https://oj.leetcode.com/problems/merge-intervals/)	| Hard	|
-|		|	55	|	[Jump Game](https://oj.leetcode.com/problems/jump-game/)	| Medium	|
+|	[Swift](./DP/JumpGame.swift) |	55	|	[Jump Game](https://oj.leetcode.com/problems/jump-game/)	| Medium	|
 |	[Swift](./Array/SpiralMatrix.swift)	|	54	|	[Spiral Matrix](https://oj.leetcode.com/problems/spiral-matrix/)	| Medium	|
 |	[Swift](./DP/MaximumSubarray.swift)	|	53	|	[Maximum Subarray](https://oj.leetcode.com/problems/maximum-subarray/)	| Medium	|
 |	[Swift](./DFS/NQueensII.swift)	|	52	|	[N-Queens II](https://oj.leetcode.com/problems/n-queens-ii/)	| Hard	|

Sort/InsertInterval.swift

@@ -0,0 +1,47 @@
+/**
+ * Question Link: https://leetcode.com/problems/insert-interval/
+ * Primary idea: First, check if nuewInterval's start is larger than one interval's end. 
+ *                      If so, save the index, otherwise save intervals
+ *               Second, keep updating a new interval if nuewInterval's end is larger then one interval's start
+ *                      If cannot find more, append the new interval to the result array
+ *               Final Step, append the rest intervals to the result array
+ *
+ * Time Complexity: O(n), Space Complexity: O(1), 
+ *
+ * Definition for an interval.
+ * public class Interval {
+ *     public var start: Int
+ *     public var end: Int
+ *     public init(_ start: Int, _ end: Int) {
+ *         self.start = start
+ *         self.end = end
+ *     }
+ * }
+ */
+
+class InsertInterval {
+    func insert(_ intervals: [Interval], _ newInterval: Interval) -> [Interval] {
+        var index = 0
+        var result: [Interval] = []
+        var tempInterval = Interval(newInterval.start, newInterval.end)
+        
+        while index < intervals.count && newInterval.start > intervals[index].end {
+            result.append(intervals[index])
+            index += 1
+        }
+        
+        while index < intervals.count && newInterval.end >= intervals[index].start {
+            let minStart = min(tempInterval.start, intervals[index].start)
+            let maxEnd = max(tempInterval.end, intervals[index].end)
+            tempInterval = Interval(minStart, maxEnd)
+            index += 1
+        }
+        result.append(tempInterval)
+        
+        for i in index ..< intervals.count {
+            result.append(intervals[i])
+        }
+        
+        return result
+    }
+}