From 2c9444579a40fa654278e535a3b8ceedddebc27a Mon Sep 17 00:00:00 2001
From: Mattrixwv <m_ellison@ymail.com>
Date: Wed, 17 Jun 2020 17:27:27 -0400
Subject: [PATCH] Added function to get all permutations of a string

---
 src/Algorithms.rs | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 src/lib.rs        | 19 ++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/src/Algorithms.rs b/src/Algorithms.rs
index 267a217..ef9b5e5 100644
--- a/src/Algorithms.rs
+++ b/src/Algorithms.rs
@@ -376,3 +376,53 @@ pub fn getDivisorsBig(goalNumber: num::BigInt) -> Vec<num::BigInt>{
 	divisors.sort();
 	return divisors;
 }
+
+//This is a function that creates all permutations of a string and returns a vector of those permutations.
+pub fn getPermutations(master: String) -> Vec::<String>{
+	return getPermutationsFull(master, 0);
+}
+fn getPermutationsFull(masterOrg: String, num: i32) -> Vec::<String>{
+	let mut master = masterOrg;
+	let mut perms = Vec::<String>::new();
+	//Check if the number is out of bounds
+	if((num >= master.len() as i32) || (num < 0)){
+		//Do nothing and return an empty array
+	}
+	//If this is the last possible recurse just return the current string
+	else if(num == (master.len() - 1) as i32){
+		perms.push(master);
+	}
+	//If there are more possible recurses, recurse with the current permutation
+	else{
+		let mut temp = getPermutationsFull(master.clone(), num + 1);
+		perms.extend(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
+		let mut cnt = 1;
+		while((num + cnt) < master.len() as i32){
+			master = swapString(master.clone(), num, (num + cnt));
+			temp = getPermutationsFull(master.clone(), num + 1);
+			perms.extend(temp);
+			master = swapString(master.clone(), num, (num + cnt));
+			cnt += 1;
+		}
+
+		//The array is not necessarily in alpha-numeric order. So if this is the full array sort it before returning
+		perms.sort();
+	}
+
+	//Return the array that was built
+	return perms;
+}
+pub fn swapString(strng: String, first: i32, second: i32) -> String{
+	let mut bytes = Vec::<u8>::new();
+	bytes.extend_from_slice(strng.as_bytes());
+	let temp = bytes[first as usize];
+	bytes[first as usize] = bytes[second as usize];
+	bytes[second as usize] = temp;
+	let mut swappedString = "".to_string();
+	for loc in 0..bytes.len(){
+		swappedString = format!("{}{}", swappedString, (bytes[loc] as char));
+	}
+	return swappedString;
+}
diff --git a/src/lib.rs b/src/lib.rs
index 65a4ff7..2641285 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -103,6 +103,25 @@ mod AlgorithmsTests{
 		let answer2 = super::Algorithms::getDivisorsBig(topNum2);
 		assert_eq!(correctAnswer2, answer2);
 	}
+	#[test]
+	fn testGetPermutations(){
+		//Test
+		let permString = "012".to_string();
+		let mut correctAnswer = Vec::<String>::new();
+		correctAnswer.extend_from_slice(&["012".to_string(), "021".to_string(), "102".to_string(), "120".to_string(), "201".to_string(), "210".to_string()]);
+		let answer = super::Algorithms::getPermutations(permString);
+		println!("answer: {:?}", answer);
+		assert_eq!(correctAnswer, answer);
+	}
+	#[test]
+	fn testSwapString(){
+		//Test 1
+		let string = "012".to_string();
+		let correctAnswer = "210".to_string();
+		let answer = super::Algorithms::swapString(string, 0, 2);
+		println!("swaped: {}", answer);
+		assert_eq!(correctAnswer, answer);
+	}
 }