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都说Rust性能好,但是也得代码写得好,猜猜下面两个代码哪个快

. - 力扣（LeetCode）

use std::collections::HashMap;
use lazy_static::lazy_static;lazy_static! {static ref DIGIT: HashMap<char, usize> = {let mut m = HashMap::new();for c in '1'..':' {m.insert(c, Solution::to_digit(c) as usize - 1);}m};
}impl Solution {pub fn to_digit(c: char) -> u32 {match c.to_digit(10) {None => 0,Some(i) => i,}}pub const SUB_INDEX: [[usize; 9]; 9] = [[0, 0, 0, 1, 1, 1, 2, 2, 2],[0, 0, 0, 1, 1, 1, 2, 2, 2],[0, 0, 0, 1, 1, 1, 2, 2, 2],[3, 3, 3, 4, 4, 4, 5, 5, 5],[3, 3, 3, 4, 4, 4, 5, 5, 5],[3, 3, 3, 4, 4, 4, 5, 5, 5],[6, 6, 6, 7, 7, 7, 8, 8, 8],[6, 6, 6, 7, 7, 7, 8, 8, 8],[6, 6, 6, 7, 7, 7, 8, 8, 8],];pub fn is_valid_sudoku(board: Vec<Vec<char>>) -> bool {let mut line_count: [[i32; 9]; 9] = [[0; 9]; 9];let mut colume_count: [[i32; 9]; 9] = [[0; 9]; 9];let mut sub_count: [[i32; 9]; 9] = [[0; 9]; 9];let mut i = 0;let mut j = 0;for line in board {for colume in line {if colume != '.' {let digit = match DIGIT.get(&colume) {Some(i) => *i,None => return false};if line_count[i][digit] == 0 {line_count[i][digit] = 1;} else {return false;}if colume_count[j][digit] == 0 {colume_count[j][digit] = 1;} else {return false;}if sub_count[Solution::SUB_INDEX[i][j]][digit] == 0 {sub_count[Solution::SUB_INDEX[i][j]][digit] = 1;} else {return false;}}j += 1;}j = 0;i += 1;}true}
}

use std::collections::HashSet;
impl Solution {pub fn is_valid_sudoku(board: Vec<Vec<char>>) -> bool {let mut row:HashSet<char> = HashSet::with_capacity(9);let mut blocks:Vec<HashSet<char>> = vec![HashSet::with_capacity(9);3];let mut col:Vec<HashSet<char>> = vec![HashSet::with_capacity(9);9];for (idx,i) in board.iter().enumerate(){if idx % 3 == 0{for i in 0..3{blocks[i].clear();}}for (jdx,&j) in i.iter().enumerate(){if j == '.'{continue;}let temp = jdx/3;if row.contains(&j) || col[jdx].contains(&j) || blocks[temp].contains(&j) {//println!("{},{}",idx,jdx);return false;}row.insert(j);col[jdx].insert(j);blocks[temp].insert(j);}row.clear();}true}
}

Perf 分析 Perf+火焰图进行性能瓶颈分析-CSDN博客

const BOARD_ARR:[[char; 9]; 9] = [['5', '3', '.', '.', '7', '.', '.', '.', '.'],['6', '.', '.', '1', '9', '5', '.', '.', '.'],['.', '9', '8', '.', '.', '.', '.', '6', '.'],['8', '.', '.', '.', '6', '.', '.', '.', '3'],['4', '.', '.', '8', '.', '3', '.', '.', '1'],['7', '.', '.', '.', '2', '.', '.', '.', '6'],['.', '6', '.', '.', '.', '.', '2', '8', '.'],['.', '.', '.', '4', '1', '9', '.', '.', '5'],['.', '.', '.', '.', '8', '.', '.', '7', '9'],];fn main() {    let mut board: Vec<Vec<char>> = Vec::new();for arr in BOARD_ARR {let line: Vec<char> = Vec::from(arr);board.push(line);}let mut result: bool = false;let start = Instant::now();for _i in 1..10000 {result = Solution::is_valid_sudoku(board.clone());}println!("is_valid_sudoku {:?}", start.elapsed());let start = Instant::now();for _i in 1..10000 {result = Solution::is_valid_sudoku2(board.clone());}println!("is_valid_sudoku2 {:?}", start.elapsed());println!("{}", result);
}

 clone比较费时:

MacBook-Pro:is_valid_sudoku mac$  ./target/release/is_valid_sudoku
is_valid_sudoku 23.554336ms
is_valid_sudoku2 66.421909ms
true

改成引用之后:

MacBook-Pro:is_valid_sudoku mac$  ./target/release/is_valid_sudoku
is_valid_sudoku 6.21774ms
is_valid_sudoku2 47.475271ms
true