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44 lines
1.1 KiB
JavaScript
44 lines
1.1 KiB
JavaScript
/**
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* File: leetcode_two_sum.js
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* Created Time: 2022-12-15
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* Author: gyt95 (gytkwan@gmail.com)
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*/
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/**
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* @param {number[]} nums
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* @param {number} target
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* @return {number[]}
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*/
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function twoSumBruteForce(nums, target) {
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let n = nums.length;
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// 两层循环，时间复杂度 O(n^2)
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for (let i = 0; i < n; i++) {
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for (let j = i + 1; j < n; j++) {
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if (nums[i] + nums[j] === target) {
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return [i, j];
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}
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}
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}
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}
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function twoSumHashTable(nums, target) {
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// 辅助哈希表，空间复杂度 O(n)
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let m = {};
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// 单层循环，时间复杂度 O(n)
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for (let i = 0; i < nums.length; i++) {
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if (m[nums[i]] !== undefined) {
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return [m[nums[i]], i];
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} else {
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m[target - nums[i]] = i;
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}
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}
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}
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/* Driver Code */
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let nums = [2, 7, 11, 15], target = 9;
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twoSumBruteForce(nums, target)
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console.log("使用暴力枚举后得到结果：", nums)
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let nums1 = [2, 7, 11, 15], target1 = 9;
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twoSumHashTable(nums1, target1)
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console.log("使用辅助哈希表后得到结果", nums1)
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