From 3b48a61fe77764c9c23d1af01c32514c53356df0 Mon Sep 17 00:00:00 2001
From: Mattrixwv <m_ellison@ymail.com>
Date: Fri, 4 Sep 2020 13:33:11 -0400
Subject: [PATCH] Added functions to get all permutations of a string

---
 CSClasses/Algorithms.cs | 43 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/CSClasses/Algorithms.cs b/CSClasses/Algorithms.cs
index 592bf72..de669cc 100644
--- a/CSClasses/Algorithms.cs
+++ b/CSClasses/Algorithms.cs
@@ -607,5 +607,48 @@ namespace mee{
 			}
 			return prod;
 		}
+		//This is a function the creates all permutations of a string and returns a list of those permutations
+		public static List<string> GetPermutations(string master){
+			return GetPermutations(master, 0);
+		}
+		public static List<string> GetPermutations(string master, int num){
+			List<string> perms = new List<string>();
+			//Check if the number is out of bounds
+			if((num >= master.Length) || (num < 0)){
+				//Do nothing and return an empty list
+			}
+			//If this is the last possible recurse just return the current string
+			else if(num == (master.Length - 1)){
+				perms.Add(master);
+			}
+			//If there are more possible recurses, the recurse with the current permutation
+			else{
+				List<string> temp = GetPermutations(master, num + 1);
+				perms.AddRange(temp);
+				//You need to swap the current letter with every possible letter after it
+				//The ones needed to swap before will happen automatically when the function recurses
+				for(int cnt = 1;(num + cnt) < master.Length;++cnt){
+					master = SwapString(master, num, (num + cnt));
+					temp = GetPermutations(master, num + 1);
+					perms.AddRange(temp);
+					master = SwapString(master, num, (num + cnt));
+				}
+
+				//The array is not necessarily in alpha-numeric order. So if this is the full array sort it before returning
+				if(num == 0){
+					perms.Sort();
+				}
+			}
+
+			//Return the list that was build
+			return perms;
+		}
+		public static string SwapString(string str, int first, int second){
+			char[] tempStr = str.ToCharArray();
+			char temp = str[first];
+			tempStr[first] = tempStr[second];
+			tempStr[second] = temp;
+			return new string(tempStr);
+		}
 	}
 }