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Add figures to replace_linear_by_hashing.md

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krahets
2023-05-09 00:36:18 +08:00
parent 53ca2144e2
commit fe69f7240d
23 changed files with 85 additions and 80 deletions
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53
codes/rust/chapter_computational_complexity/leetcode_two_sum.rs
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/*
* File: leetcode_two_sum.rs
* Created Time: 2023-01-14
* Author: xBLACICEx (xBLACKICEx@outlook.com), sjinzh (sjinzh@gmail.com)
*/
include!("../include/include.rs");
use std::collections::HashMap;
/* 方法一：暴力枚举 */
pub fn two_sum_brute_force(nums: &Vec<i32>, target: i32) -> Option<Vec<i32>> {
let size = nums.len();
// 两层循环，时间复杂度 O(n^2)
for i in 0..size - 1 {
for j in i + 1..size {
if nums[i] + nums[j] == target {
return Some(vec![i as i32, j as i32]);
}
}
}
None
}
/* 方法二：辅助哈希表 */
pub fn two_sum_hash_table(nums: &Vec<i32>, target: i32) -> Option<Vec<i32>> {
// 辅助哈希表，空间复杂度 O(n)
let mut dic = HashMap::new();
// 单层循环，时间复杂度 O(n)
for (i, num) in nums.iter().enumerate() {
match dic.get(&(target - num)) {
Some(v) => return Some(vec![*v as i32, i as i32]),
None => dic.insert(num, i as i32)
};
}
None
}
fn main() {
// ======= Test Case =======
let nums = vec![ 2, 7, 11, 15 ];
let target = 9;
// ====== Driver Code ======
// 方法一
let res = two_sum_brute_force(&nums, target).unwrap();
print!("方法一 res = ");
print_util::print_array(&res);
// 方法二
let res = two_sum_hash_table(&nums, target).unwrap();
print!("\n方法二 res = ");
print_util::print_array(&res);
}