feat(problem): 10 - summation of primes

readme.md

@@ -5,11 +5,11 @@
 
 > My solutions to many of Project Euler's problems.
 
-All of the solutions here are written in rust. [main.rs](src/main.rs) is the home to my helper command line that can As per the rules of the challenge, I may only publish the solutions to the first 100 problems here, so I will stop after that but still continue the challenge.
+All of the solutions here are written in rust. [main.rs](src/main.rs) is the home to my helper command line that can scaffold files for me quickly, prefaced with a statement of the problem! As per the rules of the challenge, I may only publish the solutions to the first 100 problems here, so I will stop after that but still continue the challenge.
 
 ## Challenge Completion
 
-<!-- completed -->9<!-- completed --> out of 100 public challenges completed.
+### <!-- completed -->10<!-- completed --> out of 100 public challenges completed.
 
 - [x] 1 - [Multiples of 3 or 5](src/bin/1.rs)
 - [x] 2 - [Even Fibonacci numbers](src/bin/2.rs)
@@ -20,7 +20,7 @@ All of the solutions here are written in rust. [main.rs](src/main.rs) is the hom
 - [x] 7 - [10001st prime](src/bin/7.rs)
 - [x] 8 - [Largest product in a series](src/bin/8.rs)
 - [x] 9 - [Special Pythagorean triplet](src/bin/9.rs)
-- [ ] 10 - Summation of primes
+- [x] 10 - [Summation of primes](src/bin/10.rs)
 - [ ] 11 - Largest product in a grid
 - [ ] 12 - Highly divisible triangular number
 - [ ] 13 - Large sum

src/bin/10.rs

@@ -0,0 +1,42 @@
+/*
+Problem 10 - Summation of primes
+
+The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
+Find the sum of all the primes below two million.
+*/
+
+// Implementation of the Sieve of Eratosthenes
+// https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes
+fn find_primes(upper_bound: usize) -> Vec<usize> {
+	let mut mask = vec![true; upper_bound];
+	let mut primes: Vec<usize> = vec![];
+
+	mask[0] = false;
+	mask[1] = false;
+
+	for i in 2..upper_bound {
+		if mask[i] {
+			primes.push(i);
+
+			let mut j = 2 * i;
+
+			while j < upper_bound {
+				mask[j] = false;
+				j += i;
+			}
+		}
+	}
+
+	return primes;
+}
+
+fn sum_of_primes(upper_bound: usize) -> usize {
+    let primes = find_primes(upper_bound);
+    return primes.iter().sum::<usize>();
+}
+
+fn main() {
+    let value = sum_of_primes(2000000);
+
+    println!("The sum of the primes up until 2000000 is {value}");
+}

src/bin/5.rs

@@ -31,9 +31,9 @@ fn gcd(a: usize, b: usize) -> usize {
 	return y;
 }
 
-fn first_value_divisible_by(start: usize, end: usize) -> usize { 
+fn first_value_divisible_by(start: usize, end: usize) -> Option<usize> { 
 	if start > end {
-		panic!("You can not start on a value higher than your end value!");
+		return None;
 	}
 
 	let mut result: usize = 1;
@@ -42,11 +42,11 @@ fn first_value_divisible_by(start: usize, end: usize) -> usize {
 		result = (result * i) / gcd(result, i);
 	}
 
-	return result;
+	return Some(result);
 }
 
 fn main() {
-	let number = first_value_divisible_by(1, 20);
+	let number = first_value_divisible_by(1, 20).unwrap();
 
 	println!("The smallest number that is divisible by all integers between 1 and 20 is {number}");
 }

src/bin/6.rs

@@ -12,9 +12,9 @@ Find the difference between the sum of the squares of the first one hundred natu
 const LOWER_BOUND: usize = 1;
 const UPPER_BOUND: usize = 100;
 
-fn sum_of_squares(lower_bound: usize, upper_bound: usize) -> usize {
+fn sum_of_squares(lower_bound: usize, upper_bound: usize) -> Option<usize> {
 	if lower_bound > upper_bound {
-		panic!("The lower bound must be less than the upper bound!");
+		return None;
 	}
 
 	let mut squares: Vec<usize> = vec![];
@@ -23,20 +23,20 @@ fn sum_of_squares(lower_bound: usize, upper_bound: usize) -> usize {
 		squares.push(i.pow(2));
 	}
 
-	return squares.iter().sum();
+	return Some(squares.iter().sum());
 }
 
-fn square_of_sum(lower_bound: usize, upper_bound: usize) -> usize {
+fn square_of_sum(lower_bound: usize, upper_bound: usize) -> Option<usize> {
 	if lower_bound > upper_bound {
-		panic!("The lower bound must be less than the upper bound!");
+		return None;
 	}
 
-	return ((lower_bound..(upper_bound + 1)).sum::<usize>()).pow(2);
+	return Some(((lower_bound..(upper_bound + 1)).sum::<usize>()).pow(2));
 }
 
 fn main() {
-	let squared_sum = square_of_sum(LOWER_BOUND, UPPER_BOUND);
-	let summed_squares = sum_of_squares(LOWER_BOUND, UPPER_BOUND);
+	let squared_sum = square_of_sum(LOWER_BOUND, UPPER_BOUND).unwrap();
+	let summed_squares = sum_of_squares(LOWER_BOUND, UPPER_BOUND).unwrap();
 	let difference = squared_sum - summed_squares;
 
 	println!("For the numbers between {LOWER_BOUND} and {UPPER_BOUND}, the difference between the square of the sum and the sum of the squares is {difference}");

src/bin/7.rs

@@ -10,32 +10,25 @@ use std::f64::consts::E;
 // Implementation of the Sieve of Eratosthenes
 // https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes
 fn find_primes(upper_bound: usize) -> Vec<usize> {
-	let mut values: Vec<bool> = (2..(upper_bound + 1)).map(|_| true).collect();
-	let mut i = 2;
+	let mut mask = vec![true; upper_bound];
+	let mut primes: Vec<usize> = vec![];
 
-	// Adjust values array
-	while i < (upper_bound as f64).sqrt() as usize {
-		if values[i] {
-			let mut j = i.pow(2);
+	mask[0] = false;
+	mask[1] = false;
+
+	for i in 2..upper_bound {
+		if mask[i] {
+			primes.push(i);
+
+			let mut j = 2 * i;
 
 			while j < upper_bound {
-				values[j] = false;
+				mask[j] = false;
 				j += i;
 			}
 		}
-
-		i += 1;
 	}
 
-	// Find the indexes where the values are true
-	let mut primes: Vec<usize> = vec![];
-
-	for i in 0..values.len() {
-		if values[i] {
-			primes.push(i);
-		}
-	}
-	
 	return primes;
 }
 
@@ -52,13 +45,17 @@ fn upper_bound_for_nth_prime(n: usize) -> usize {
 	return n * (ln_n + ln_n.log(E)).ceil() as usize;
 }
 
-fn nth_prime(n: usize) -> usize {
+fn nth_prime(n: usize) -> Option<usize> {
+	if n < 1 {
+		return None;
+	}
+
 	let primes = find_primes(upper_bound_for_nth_prime(n));
-	return primes[n - 1];
+	return Some(primes[n - 1]);
 }
 
 fn main() {
-	let number = nth_prime(10001);
+	let number = nth_prime(10001).unwrap();
 
 	println!("The 10,001st prime number is {number}");
 }

src/bin/8.rs

@@ -29,9 +29,9 @@ const NUMBER: &str = "7316717653133062491922511967442657474235534919493496983520
 
 const ADJACENT_DIGITS: usize = 13;
 
-fn largest_product(number: &str, adjacent_digits: usize) -> usize {
+fn largest_product(number: &str, adjacent_digits: usize) -> Option<usize> {
 	if adjacent_digits > number.len() {
-		panic!("I can not check for the product of {} adjacent digits when there is only {} digits in the number!", adjacent_digits, number.len());
+		return None;
 	}
 
 	let mut cursor_index = 0;
@@ -68,11 +68,11 @@ fn largest_product(number: &str, adjacent_digits: usize) -> usize {
 	products.sort();
 	products.reverse();
 
-	return products[0];
+	return Some(products[0]);
 }
 
 fn main() {
-	let value = largest_product(NUMBER, ADJACENT_DIGITS);
+	let value = largest_product(NUMBER, ADJACENT_DIGITS).unwrap();
 	
 	println!("The thirteen adjacent digits in the number that have the greatest product have a product of {value}");
 }

src/bin/9.rs

@@ -21,21 +21,21 @@ There exists exactly one Pythagorean triplet for which  a  +  b  +  c  = 1000. F
 // b = (2an - n^2)/(2a - 2n)
 // c = n - a - b
 
-fn triplet_with_sum(sum: isize) -> (isize, isize, isize) {
+fn triplet_with_sum(sum: isize) -> Option<(isize, isize, isize)> {
     for a in 1..(sum + 1) {
         let b: isize = ((2 * a * sum) - sum.pow(2)) / (2 * (a - sum));
         let c: isize  = sum - a - b;
 
         if a.pow(2) + b.pow(2) == c.pow(2) {
-            return (a, b, c);
+            return Some((a, b, c));
         }
     }
 
-    panic!("A triplet could not be found with the sum {sum}!");
+    return None;
 }
 
 fn main() {
-    let (a, b, c) = triplet_with_sum(1000);
+    let (a, b, c) = triplet_with_sum(1000).unwrap();
     
     println!("a = {a}, b = {b}, c = {c} // abc = {}", a * b * c);
 }

src/main.rs

@@ -97,7 +97,7 @@ Problem {} - {}
 */
 
 fn main() {{
-    println!(\"Hello World!\");  
+    println!(\"Hello World!\");
 }}", 
         problem_number,
         html_escape::decode_html_entities(&mut title).to_string(),
@@ -171,12 +171,10 @@ fn main() {{
     Ok(())
 }
 
-// todo: runner
-
 fn main() {
     let value = Value::parse();
 
     match value.command {
-        Commands::New => new().unwrap(),
+        Commands::New => new().unwrap()
     }
 }