Add Largest Time for Given Digits C#

README.md

@@ -2,6 +2,13 @@
 
 https://leetcode.com
 
+## September LeetCoding Challenge
+Click [here](https://leetcode.com/explore/challenge/card/september-leetcoding-challenge) for problem descriptions.
+
+Solutions in various programming languages are provided. Enjoy it.
+
+1. [Largest Time for Given Digits](https://github.com/AlgoStudyGroup/Leetcode/tree/master/September-LeetCoding-Challenge/01-Largest-Time-for-Given-Digits)
+
 ## August LeetCoding Challenge
 Click [here](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/) for problem descriptions.
 

September-LeetCoding-Challenge/01-Largest-Time-for-Given-Digits/Largest-Time-for-Given-Digits.cs

@@ -0,0 +1,25 @@
+public class Solution {
+    public string LargestTimeFromDigits(int[] A) {
+        var l = new Queue<string>();
+        l.Enqueue("");
+
+        for(int n=0; n<A.Length; n++){
+            for(int size = l.Count; size>0; size--){
+                var s = l.Dequeue();
+                for(int i=0; i<=s.Length; i++){
+                    l.Enqueue(s.Substring(0,i) + A[n] + s.Substring(i));
+                }
+            }
+        }
+
+        var largest = "";
+        foreach(var s in l){
+            var t = s.Substring(0, 2) + ":" + s.Substring(2);
+            if(t[3] < '6' && t.CompareTo("24:00") <0 && t.CompareTo(largest)>0){
+                largest = t;
+            }
+        }
+
+        return largest;
+    }
+}