diff --git a/src/Problems.rs b/src/Problems.rs index 06fd858..3eb40e9 100644 --- a/src/Problems.rs +++ b/src/Problems.rs @@ -42,3 +42,4 @@ pub mod Problem16; pub mod Problem17; pub mod Problem18; pub mod Problem19; +pub mod Problem20; diff --git a/src/Problems/Problem20.rs b/src/Problems/Problem20.rs new file mode 100644 index 0000000..d5b37b3 --- /dev/null +++ b/src/Problems/Problem20.rs @@ -0,0 +1,65 @@ +//ProjectEulerRust/src/Problems/Problems20.rs +//Matthew Ellison +// Created: 06-17-20 +//Modified: 06-17-20 +//What is the sum of the digits of 100!? +//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{ + "What is the sum of the digits of 100!?".to_string() +} + +pub fn solve() -> Answer{ + let TOP_NUM = 100; + //The number that is being generated + let mut number = num::BigInt::from(1); + let mut sum = 0; + + //Start the timer + let mut timer = myClasses::Stopwatch::Stopwatch::new(); + timer.start(); + + //Run through every number from 1 to 100 and multiply it by the current num to generate 100! + for cnt in (2..=TOP_NUM).rev(){ + number *= num::BigInt::from(cnt); + } + + //Get a string of the number because it is easier to pull apart the individual characters + let numString = number.to_string(); + //Run through every character in the string, convert it back to an integer and add it to the running sum + for cnt in numString.chars(){ + sum += cnt.to_digit(10).unwrap(); + } + + //Stop the timer + timer.stop(); + + //Return the results + return Answer::new(format!("{}! = {}\nThe sum of the digits is: {}", TOP_NUM, number, sum), timer.getString()); +} + +/* Results: +100! = 93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000 +The sum of the digits is: 648 +It took 18.000 microseconds to solve this problem +*/ diff --git a/src/main.rs b/src/main.rs index cd69649..ef2dcb3 100644 --- a/src/main.rs +++ b/src/main.rs @@ -33,8 +33,9 @@ mod Problems; #[derive(PartialEq)] enum Selections{EMPTY, SOLVE, DESCRIPTION, LIST, EXIT, SIZE} -static problemNumbers: [u32; 20] = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, - 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]; +static problemNumbers: [u32; 21] = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, + 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, + 20]; fn main(){ let mut selection = Selections::EMPTY; @@ -207,6 +208,10 @@ fn solveProblem(problemNumber: u32){ println!("{}", Problems::Problem19::getDescription()); println!("{}", Problems::Problem19::solve()); } + else if(problemNumber == 20){ + println!("{}", Problems::Problem20::getDescription()); + println!("{}", Problems::Problem20::solve()); + } } fn descriptionMenu(){ //Give some extra space to print the description @@ -289,6 +294,9 @@ fn printDescription(problemNumber: u32){ else if(problemNumber == 19){ println!("{}", Problems::Problem19::getDescription()); } + else if(problemNumber == 20){ + println!("{}", Problems::Problem20::getDescription()); + } } fn getProblemNumber() -> u32{ println!("Enter a problem number: ");