diff --git a/src/Problems.rs b/src/Problems.rs
index 3eb40e9..cf5b909 100644
--- a/src/Problems.rs
+++ b/src/Problems.rs
@@ -43,3 +43,4 @@ pub mod Problem17;
pub mod Problem18;
pub mod Problem19;
pub mod Problem20;
+pub mod Problem21;
diff --git a/src/Problems/Problem21.rs b/src/Problems/Problem21.rs
new file mode 100644
index 0000000..3bf6130
--- /dev/null
+++ b/src/Problems/Problem21.rs
@@ -0,0 +1,101 @@
+//ProjectEulerRust/src/Problems/Problems21.rs
+//Matthew Ellison
+// Created: 06-17-20
+//Modified: 06-17-20
+//Evaluate the sum of all the amicable numbers under 10000
+//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/RustClasses
+/*
+ Copyright (C) 2020 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 .
+*/
+
+
+extern crate myClasses;
+use crate::Problems::Answer::Answer;
+
+pub fn getDescription() -> String{
+ "Evaluate the sum of all the amicable numbers under 10000".to_string()
+}
+
+pub fn solve() -> Answer{
+ let LIMIT = 10000;
+ //Setup the variables
+ let mut divisorSum = Vec::::new();
+ //Make sure the array is filled with 0's
+ while(divisorSum.len() < LIMIT){
+ divisorSum.push(0);
+ }
+
+ //Start the timer
+ let mut timer = myClasses::Stopwatch::Stopwatch::new();
+ timer.start();
+
+ //Generate the divisors of all numbers < 10000, get their sum, and add it to the list
+ for cnt in 1..LIMIT{
+ let mut divisors = myClasses::Algorithms::getDivisors(cnt as i64);
+ if(divisors.len() > 1){
+ divisors.remove(divisors.len() - 1);
+ }
+ divisorSum[cnt] = divisors.iter().sum();
+ }
+ //Check every sum of divisors in the list for matching sum
+ let mut amicable = Vec::::new();
+ for cnt in 1..divisorSum.len(){
+ let sum = divisorSum[cnt];
+ //If the sum is greater than the number of divisors then it is impossible to be amicable. Skip the number and continue
+ if(sum >= divisorSum.len() as i64){
+ continue;
+ }
+ //We know that divisorSum.at(cnt) == sum, so if divisorSum.at(sum) == cnt we found an amicable number
+ if(divisorSum[sum as usize] == cnt as i64){
+ //A number can't be amicable with itself
+ if(sum == cnt as i64){
+ continue;
+ }
+ //Add it to the array of amicable numbers
+ amicable.push(cnt as i64);
+ }
+ }
+
+ //Stop the timer
+ timer.stop();
+
+ //Sort the array for neatness
+ amicable.sort();
+
+ //Return the results
+ let mut answerString = format!("All amicable numbers less than {} are\n", LIMIT);
+ for cnt in 0..amicable.len(){
+ answerString = format!("{}{}\n", answerString, amicable[cnt]);
+ }
+ answerString = format!("{}The sum of all of these amicable numbers is {}", answerString, amicable.iter().sum::());
+ return Answer::new(answerString, timer.getString());
+}
+
+/* Results:
+All amicable numbers less than 10000 are
+220
+284
+1184
+1210
+2620
+2924
+5020
+5564
+6232
+6368
+The sum of all of these amicable numbers is 31626
+It took 5.792 milliseconds to solve this problem
+*/
diff --git a/src/main.rs b/src/main.rs
index ef2dcb3..89e4093 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,7 +1,7 @@
//ProjectEulerRust/src/main.rs
//Matthew Ellison
// Created: 06-11-20
-//Modified: 06-15-20
+//Modified: 06-17-20
//This is a driver function for the Project Euler solutions in Rust
//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/RustClasses
/*
@@ -33,9 +33,9 @@ mod Problems;
#[derive(PartialEq)]
enum Selections{EMPTY, SOLVE, DESCRIPTION, LIST, EXIT, SIZE}
-static problemNumbers: [u32; 21] = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+static problemNumbers: [u32; 22] = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
- 20];
+ 20, 21];
fn main(){
let mut selection = Selections::EMPTY;
@@ -212,6 +212,10 @@ fn solveProblem(problemNumber: u32){
println!("{}", Problems::Problem20::getDescription());
println!("{}", Problems::Problem20::solve());
}
+ else if(problemNumber == 21){
+ println!("{}", Problems::Problem21::getDescription());
+ println!("{}", Problems::Problem21::solve());
+ }
}
fn descriptionMenu(){
//Give some extra space to print the description
@@ -297,6 +301,9 @@ fn printDescription(problemNumber: u32){
else if(problemNumber == 20){
println!("{}", Problems::Problem20::getDescription());
}
+ else if(problemNumber == 21){
+ println!("{}", Problems::Problem21::getDescription());
+ }
}
fn getProblemNumber() -> u32{
println!("Enter a problem number: ");