54 lines
1.5 KiB
Rust
54 lines
1.5 KiB
Rust
/*
|
|
* File: two_sum.rs
|
|
* Created Time: 2023-01-14
|
|
* Author: xBLACICEx (xBLACKICEx@outlook.com), codingonion (coderonion@gmail.com)
|
|
*/
|
|
|
|
include!("../include/include.rs");
|
|
|
|
use std::collections::HashMap;
|
|
|
|
/* Method one: Brute force enumeration */
|
|
pub fn two_sum_brute_force(nums: &Vec<i32>, target: i32) -> Option<Vec<i32>> {
|
|
let size = nums.len();
|
|
// Two-layer loop, time complexity is 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
|
|
}
|
|
|
|
/* Method two: Auxiliary hash table */
|
|
pub fn two_sum_hash_table(nums: &Vec<i32>, target: i32) -> Option<Vec<i32>> {
|
|
// Auxiliary hash table, space complexity is O(n)
|
|
let mut dic = HashMap::new();
|
|
// Single-layer loop, time complexity is 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 = 13;
|
|
|
|
// ====== Driver Code ======
|
|
// Method one
|
|
let res = two_sum_brute_force(&nums, target).unwrap();
|
|
print!("Method one res =");
|
|
print_util::print_array(&res);
|
|
// Method two
|
|
let res = two_sum_hash_table(&nums, target).unwrap();
|
|
print!("\nMethod two result res = ");
|
|
print_util::print_array(&res);
|
|
}
|