From e9ffc487ae9758d064ddaeb60d60643d39a20215 Mon Sep 17 00:00:00 2001
From: Mattrixwv <m_ellison@ymail.com>
Date: Sun, 14 Jun 2020 18:44:12 -0400
Subject: [PATCH] Added solution to problem 4

---
 src/Problems.rs          |  1 +
 src/Problems/Problem4.rs | 69 ++++++++++++++++++++++++++++++++++++++++
 src/main.rs              |  9 +++++-
 3 files changed, 78 insertions(+), 1 deletion(-)
 create mode 100644 src/Problems/Problem4.rs

diff --git a/src/Problems.rs b/src/Problems.rs
index 685288d..c39f4b1 100644
--- a/src/Problems.rs
+++ b/src/Problems.rs
@@ -9,3 +9,4 @@ pub mod Answer;
 pub mod Problem1;
 pub mod Problem2;
 pub mod Problem3;
+pub mod Problem4;
diff --git a/src/Problems/Problem4.rs b/src/Problems/Problem4.rs
new file mode 100644
index 0000000..4fad4b8
--- /dev/null
+++ b/src/Problems/Problem4.rs
@@ -0,0 +1,69 @@
+//ProjectEulerRust/src/Problems/Problems4.rs
+//Matthew Ellison
+// Created: 06-14-20
+//Modified: 06-14-20
+//Find the largest palindrome made from the product of two 3-digit numbers
+//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/JavaClasses
+/*
+	Copyright (C) 2019  Matthew Ellison
+
+	This program is free software: you can redistribute it and/or modify
+	it under the terms of the GNU Lesser General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU Lesser General Public License for more details.
+
+	You should have received a copy of the GNU Lesser General Public License
+	along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+extern crate myClasses;
+use crate::Problems::Answer::Answer;
+
+
+pub fn getDescription() -> String{
+	"Find the largest palindrome made from the product of two 3-digit numbers".to_string()
+}
+
+pub fn solve() -> Answer{
+	let START_NUM = 100;
+	let END_NUM = 999;
+	//Start the timer
+	let mut timer = myClasses::Stopwatch::Stopwatch::new();
+	timer.start();
+
+	let mut palindromes = Vec::<i64>::new();
+
+	//Start at the first 3-digit number and check every one up to the last 3-digit number
+	for firstNum in START_NUM..END_NUM{
+		//You can start at the location of the first number because everything before that has already been tested. (100 * 101 == 101 * 100)
+		for secondNum in firstNum..END_NUM{
+			//Get the product of the numbers
+			let product = firstNum * secondNum;
+			//Change the number into a string
+			let productString: String = product.to_string();
+			//Reverse the string
+			let reverseString: String = productString.chars().rev().collect();
+
+			//If the number and it's reverse are the same it is a palindrome so add it to the list
+			if(productString == reverseString){
+				palindromes.push(product);
+			}
+			//If it's not a palindrome ignore it and move to the next number
+		}
+	}
+
+	//Stop the timer
+	timer.stop();
+
+	//Sort the palindromes so that the last one is the largest
+	palindromes.sort();
+
+	//Return the results
+	return Answer::new(format!("The largest palindrome is {}", palindromes[palindromes.len() - 1]), timer.getString());
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 3489ccd..6a9ed89 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -16,7 +16,7 @@ mod Problems;
 #[derive(PartialEq)]
 enum Selections{EMPTY, SOLVE, DESCRIPTION, LIST, EXIT, SIZE}
 
-static problemNumbers: [u32; 4] = [0, 1, 2, 3];
+static problemNumbers: [u32; 5] = [0, 1, 2, 3, 4];
 
 fn main(){
 	let mut selection = Selections::EMPTY;
@@ -125,6 +125,10 @@ fn solveProblem(problemNumber: u32){
 		println!("{}", Problems::Problem3::getDescription());
 		println!("{}", Problems::Problem3::solve());
 	}
+	else if(problemNumber == 4){
+		println!("{}", Problems::Problem4::getDescription());
+		println!("{}", Problems::Problem4::solve());
+	}
 }
 fn descriptionMenu(){
 	//Give some extra space to print the description
@@ -159,6 +163,9 @@ fn printDescription(problemNumber: u32){
 	else if(problemNumber == 3){
 		println!("{}", Problems::Problem3::getDescription());
 	}
+	else if(problemNumber == 4){
+		println!("{}", Problems::Problem4::getDescription());
+	}
 }
 fn getProblemNumber() -> u32{
 	println!("Enter a problem number: ");