diff --git a/c/152-Maximum-Product-Subarray.c b/c/152-Maximum-Product-Subarray.c
new file mode 100644
index 000000000..d294228ba
--- /dev/null
+++ b/c/152-Maximum-Product-Subarray.c
@@ -0,0 +1,21 @@
+int maxProduct(int* nums, int numsSize){
+    int res = nums[0], curMin = 1, curMax = 1;
+    
+    for (int i = 0; i < numsSize; i++) {
+        int temp = curMax * nums[i];
+        curMax = max(max(nums[i] * curMax, nums[i] * curMin), nums[i]);
+        curMin = min(min(temp, nums[i] * curMin), nums[i]);
+        res = max(res, curMax);
+    }
+    return res;
+}
+
+// C doesn't have a built-in max function
+int max(int a, int b) {
+    return (a > b) ? a : b;
+}
+
+// C doesn't have a built-in min function
+int min(int a, int b) {
+    return (a < b) ? a : b;
+}
\ No newline at end of file
diff --git a/csharp/153-Find-Minimum-in-Rotated-Sorted-Array.cs b/csharp/153-Find-Minimum-in-Rotated-Sorted-Array.cs
new file mode 100644
index 000000000..3afc55e86
--- /dev/null
+++ b/csharp/153-Find-Minimum-in-Rotated-Sorted-Array.cs
@@ -0,0 +1,18 @@
+public class Solution {
+    public int FindMin(int[] nums) {
+        int left = 0, right = nums.Length - 1;
+        while (left <= right) {
+            if (nums[left] <= nums[right]) {
+                return nums[left];
+            }
+            int mid = (left + right) / 2;
+            if (nums[mid] >= nums[left]) {
+                left = mid + 1;
+            }
+            else {
+                right = mid;
+            }
+        }
+        return 0;
+    }
+}
\ No newline at end of file
diff --git a/csharp/309-Best-Time-to-Buy-and-Sell-Stock-With-Cooldown.cs b/csharp/309-Best-Time-to-Buy-and-Sell-Stock-With-Cooldown.cs
new file mode 100644
index 000000000..02973c1f8
--- /dev/null
+++ b/csharp/309-Best-Time-to-Buy-and-Sell-Stock-With-Cooldown.cs
@@ -0,0 +1,13 @@
+public class Solution {
+    public int MaxProfit(int[] prices) {
+        int sold = 0, rest = 0, hold = Int32.MinValue;
+        
+        for (int i = 0; i < prices.Length; i++) {
+            int prevSold = sold;
+            sold = hold + prices[i];
+            hold = Math.Max(hold, rest - prices[i]);
+            rest = Math.Max(rest, prevSold);
+        }
+        return Math.Max(sold, rest);
+    }
+}
\ No newline at end of file
diff --git a/go/152-Maximum-Product-Subarray.go b/go/152-Maximum-Product-Subarray.go
new file mode 100644
index 000000000..b8a6a77fa
--- /dev/null
+++ b/go/152-Maximum-Product-Subarray.go
@@ -0,0 +1,27 @@
+func maxProduct(nums []int) int {
+    res, curMin, curMax := nums[0], 1, 1
+    
+    for i := 0; i < len(nums); i++ {
+        temp := curMax * nums[i]
+        curMax = max(max(nums[i] * curMax, nums[i] * curMin), nums[i])
+        curMin = min(min(temp, nums[i] * curMin), nums[i])
+        res = max(res, curMax)
+    }
+    return res
+}
+
+// Golang does not have a built-in max for integers
+func max(a int, b int) int {
+    if (a > b) {
+        return a
+    }
+    return b
+}
+
+// Golang does not have a built-in min for integers
+func min(a int, b int) int {
+    if (a < b) {
+        return a
+    }
+    return b
+}
\ No newline at end of file
diff --git a/go/66-Plus-One.go b/go/66-Plus-One.go
new file mode 100644
index 000000000..4e2849149
--- /dev/null
+++ b/go/66-Plus-One.go
@@ -0,0 +1,12 @@
+func plusOne(digits []int) []int {
+    for i := len(digits) - 1; i >= 0; i-- {
+        if digits[i] < 9 {
+            digits[i] += 1
+            return digits
+        }
+        digits[i] = 0
+    }
+    digits[0] = 1
+    digits = append(digits, 0)
+    return digits
+}
\ No newline at end of file
diff --git a/kotlin/152-Maximum-Product-Subarray.kt b/kotlin/152-Maximum-Product-Subarray.kt
new file mode 100644
index 000000000..db1ecf005
--- /dev/null
+++ b/kotlin/152-Maximum-Product-Subarray.kt
@@ -0,0 +1,15 @@
+class Solution {
+    fun maxProduct(nums: IntArray): Int {
+        var res = nums[0]
+        var curMin = 1
+        var curMax = 1
+        
+        for (n in nums) {
+            val temp = curMax * n
+            curMax = maxOf(n * curMax, n * curMin, n)
+            curMin = minOf(temp, n * curMin, n)
+            res = maxOf(res, curMax)
+        }
+        return res
+    }
+}
\ No newline at end of file
diff --git a/swift/141-Linked-List-Cycle.swift b/swift/141-Linked-List-Cycle.swift
new file mode 100644
index 000000000..4a407eea6
--- /dev/null
+++ b/swift/141-Linked-List-Cycle.swift
@@ -0,0 +1,31 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     public var val: Int
+ *     public var next: ListNode?
+ *     public init(_ val: Int) {
+ *         self.val = val
+ *         self.next = nil
+ *     }
+ * }
+ */
+
+class Solution {
+    func hasCycle(_ head: ListNode?) -> Bool {
+        if head === nil {
+            return false
+        }
+        
+        var slow = head, fast = head
+        
+        while fast != nil && fast?.next != nil {
+            slow = slow?.next
+            fast = fast?.next?.next
+            
+            if fast === slow {
+                return true
+            }
+        }
+        return false
+    }
+}
\ No newline at end of file
diff --git a/swift/152-Maximum-Product-Subarray.swift b/swift/152-Maximum-Product-Subarray.swift
new file mode 100644
index 000000000..7ef3132d5
--- /dev/null
+++ b/swift/152-Maximum-Product-Subarray.swift
@@ -0,0 +1,15 @@
+class Solution {
+    func maxProduct(_ nums: [Int]) -> Int {
+        var res = nums[0]
+        var curMin = 1
+        var curMax = 1
+        
+        for n in nums {
+            let temp = curMax * n
+            curMax = max(n * curMax, n * curMin, n)
+            curMin = min(temp, n * curMin, n)
+            res = max(res, curMax)
+        }
+        return res
+    }
+}
\ No newline at end of file
diff --git a/swift/19-Remove-Nth-Node-From-End-of-List.swift b/swift/19-Remove-Nth-Node-From-End-of-List.swift
new file mode 100644
index 000000000..e065cbb99
--- /dev/null
+++ b/swift/19-Remove-Nth-Node-From-End-of-List.swift
@@ -0,0 +1,31 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     public var val: Int
+ *     public var next: ListNode?
+ *     public init() { self.val = 0; self.next = nil; }
+ *     public init(_ val: Int) { self.val = val; self.next = nil; }
+ *     public init(_ val: Int, _ next: ListNode?) { self.val = val; self.next = next; }
+ * }
+ */
+class Solution {
+    func removeNthFromEnd(_ head: ListNode?, _ n: Int) -> ListNode? {
+        if head === nil {
+            return head
+        }
+        var slow = head, fast = head
+        for i in 1...n + 1 {
+            if (slow === nil) {
+                return head?.next
+            }
+            slow = slow?.next
+        }
+        
+        while slow != nil {
+            slow = slow?.next
+            fast = fast?.next
+        }
+        fast?.next = fast?.next?.next
+        return head
+    }
+}
\ No newline at end of file
diff --git a/swift/206-Reverse-Linked-List.swift b/swift/206-Reverse-Linked-List.swift
new file mode 100644
index 000000000..cfbb6850c
--- /dev/null
+++ b/swift/206-Reverse-Linked-List.swift
@@ -0,0 +1,28 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     public var val: Int
+ *     public var next: ListNode?
+ *     public init() { self.val = 0; self.next = nil; }
+ *     public init(_ val: Int) { self.val = val; self.next = nil; }
+ *     public init(_ val: Int, _ next: ListNode?) { self.val = val; self.next = next; }
+ * }
+ */
+class Solution {
+    func reverseList(_ head: ListNode?) -> ListNode? {
+        if (head === nil || head?.next === nil) {
+            return head
+        }
+        
+        var prev: ListNode? = nil
+        var curr = head, next = curr?.next
+        
+        while curr != nil {
+            next = curr?.next
+            curr?.next = prev
+            prev = curr
+            curr = next
+        }
+        return prev
+    }
+}
\ No newline at end of file
diff --git a/swift/213-House-Robber-II.swift b/swift/213-House-Robber-II.swift
new file mode 100644
index 000000000..629389d0f
--- /dev/null
+++ b/swift/213-House-Robber-II.swift
@@ -0,0 +1,27 @@
+class Solution {
+    func rob(_ nums: [Int]) -> Int {
+        let size = nums.count
+        
+        if size == 1 {
+            return nums[0]
+        }
+        
+        let range1 = robber(nums, 0, size - 2)
+        let range2 = robber(nums, 1, size - 1)
+        
+        return max(range1, range2)
+    }
+    
+    func robber(_ nums: [Int], _ start: Int, _ end: Int) -> Int {
+        var prev = 0
+        var curr = 0
+        var next = 0
+        
+        for i in start...end {
+            next = max(prev + nums[i], curr)
+            prev = curr
+            curr = next
+        }
+        return curr
+    }
+}
\ No newline at end of file
diff --git a/swift/57-Insert-Interval.swift b/swift/57-Insert-Interval.swift
new file mode 100644
index 000000000..2e6351298
--- /dev/null
+++ b/swift/57-Insert-Interval.swift
@@ -0,0 +1,28 @@
+class Solution {
+    func insert(_ intervals: [[Int]], _ newInterval: [Int]) -> [[Int]] {
+        var res : [[Int]] = []
+        var i = 0
+        let n = intervals.count
+        
+        // parameters are immutable in Swift
+        var currInterval = newInterval
+        
+        while i < n && intervals[i][1] < newInterval[0] {
+            res.append(intervals[i])
+            i += 1
+        }
+        
+        while i < n && intervals[i][0] <= currInterval[1] {
+            currInterval[0] = min(currInterval[0], intervals[i][0])
+            currInterval[1] = max(currInterval[1], intervals[i][1])
+            i += 1
+        }
+        res.append(currInterval)
+        
+        while i < n {
+            res.append(intervals[i])
+            i += 1
+        }
+        return res
+    }
+}
\ No newline at end of file
diff --git a/swift/72-Edit-Distance.swift b/swift/72-Edit-Distance.swift
new file mode 100644
index 000000000..5dd2b87f9
--- /dev/null
+++ b/swift/72-Edit-Distance.swift
@@ -0,0 +1,45 @@
+class Solution {
+    func minDistance(_ word1: String, _ word2: String) -> Int {
+        // No operations needed if strings match
+        if word1 == word2 {
+            return 0
+        }
+        
+        let m = word1.count, n = word2.count
+        
+        // if one word has no characters, min operations is length of other word
+        if m == 0 {
+            return n
+        }
+        if n == 0 {
+            return m
+        }
+        
+        var prev = 0
+        var curr = Array(repeating: 0, count: n + 1)
+        
+        // convert the strings into an array
+        let newWord1 = Array(word1)
+        let newWord2 = Array(word2)
+        
+        for j in 1...n {
+            curr[j] = j
+        }
+        
+        for i in 1...m {
+            var prev = curr[0]
+            curr[0] = i
+            for j in 1...n {
+                let temp = curr[j]
+                if newWord1[i - 1] == newWord2[j - 1] {
+                    curr[j] = prev
+                }
+                else {
+                    curr[j] = min(prev, min(curr[j - 1], curr[j])) + 1
+                }
+                prev = temp
+            }
+        }
+        return curr[n]
+    }
+}
\ No newline at end of file