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