34: Improve solution for Rust track exercise "Nth Prime".

Dependencies

• [2] XDEY7SNL 31: Improve solution for Rust track exercise "Raindrops".
• [3] VH5OFL55 32: Improve solution for Rust track exercise "Nth Prime".
• [4] JZN2AQ3E 10: Add Rust track exercise "nth-prime".
• [5] ERYD4CD7 11: Add solution for Rust track exercise "Nth Prime".
• [6] IXMBS6ZP 29: Improve solution for Rust track exercise "Nth Prime".
• [7] UTP7D53Q 12: Improve solution for Rust track exercise "Nth Prime".
• [8] EUWYCVLU 17: Improve solution for Rust track exercise "Nth Prime".
• [9] KWE5K6XL 23: Fix panix on input `12` for solution for Rust track exercise "Nth Prime".
• [10] ZSKHCSQ5 30: Fix regression introduced in solution for Rust track exercise "Nth Prime".

Change contents

• replacement in rust/nth-prime/src/lib.rs at line 6
  [4.545]→[4.0:22](∅→∅)
  − * Skips even numbers.
  [4.545]

  [4.0]
  + * Odd numbers only (wheel factorisation with base 2).
• replacement in rust/nth-prime/src/lib.rs at line 22
  [4.264]→[4.783:896](∅→∅),[4.783]→[4.783:896](∅→∅),[4.896]→[4.265:350](∅→∅)
  − // Approximated size of the list required using the inverse of an approximation of the prime-counting function.

  − let list_size = (corrected_n * (corrected_n * corrected_n.ln()).ln()) as usize + 1;
  [4.264]

  [4.984]
  + // Approximated size of the list required using the inverse of an approximation of the prime-counting function, halved (as we're only interested in odd numbers).

  + let list_size = (corrected_n * (corrected_n * corrected_n.ln()).ln() / 2.0) as usize + 1;
• replacement in rust/nth-prime/src/lib.rs at line 31
  [4.1175]→[3.0:45](∅→∅)
  − [false, true].repeat((list_size / 2) + 1),
  [4.1175]

  [4.23]
  + vec![true; list_size],
• replacement in rust/nth-prime/src/lib.rs at line 35
  [4.123]→[4.123:161](∅→∅)
  − for index in (3..limit).step_by(2) {
  [4.123]

  [4.1239]
  + for index in 1..limit {
• replacement in rust/nth-prime/src/lib.rs at line 40
  [2.887]→[4.1369:1394](∅→∅),[4.1369]→[4.1369:1394](∅→∅)
  − return index as u32;
  [2.887]

  [4.26]
  + return (index * 2 + 1) as u32;
• replacement in rust/nth-prime/src/lib.rs at line 42
  [4.31]→[4.162:275](∅→∅)
  − (index.pow(2)..list_size)

  − .step_by(index)

  − .for_each(|multiple| {

  − list[multiple] = false;

  − });
  [4.31]

  [4.31]
  + for multiple in (((index * 2 + 1).pow(2) - 1) / 2..list_size).step_by(index * 2 + 1) {

  + list[multiple] = false;

  + }
• replacement in rust/nth-prime/src/lib.rs at line 47
  [4.38]→[4.38:39](∅→∅),[4.39]→[4.276:399](∅→∅),[4.399]→[2.888:950](∅→∅),[2.950]→[4.478:548](∅→∅),[4.478]→[4.478:548](∅→∅)
  −

  − if limit & 1 == 1 {

  − for index in (limit..list_size).step_by(2) {

  − if list[index] {

  − count += 1;

  − if count > n {

  − // Might panic if values greater than u32::MAX are cast.

  − return index as u32;

  − }

  − }

  − }

  − } else {

  − if list[limit] {
  [4.38]

  [4.91]
  + for index in limit..list_size {

  + if list[index] {
• replacement in rust/nth-prime/src/lib.rs at line 52
  [2.1012]→[4.549:574](∅→∅),[4.202]→[4.549:574](∅→∅)
  − return limit as u32;
  [2.1012]

  [4.574]
  + return (index * 2 + 1) as u32;
• edit in rust/nth-prime/src/lib.rs at line 55
  [4.583]→[4.583:692](∅→∅),[4.692]→[2.1013:1075](∅→∅),[2.1075]→[4.771:803](∅→∅),[4.771]→[4.771:803](∅→∅),[4.227]→[4.1520:1529](∅→∅),[4.803]→[4.1520:1529](∅→∅),[4.1520]→[4.1520:1529](∅→∅)
  −

  − for index in ((limit + 1)..list_size).step_by(2) {

  − if list[index] {

  − count += 1;

  − if count > n {

  − // Might panic if values greater than u32::MAX are cast.

  − return index as u32;

  − }

  − }

  − }