46 lines
1.3 KiB
C++
46 lines
1.3 KiB
C++
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/**
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* File: worst_best_time_complexity.cpp
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* Created Time: 2022-11-25
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* Author: krahets (krahets@163.com)
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*/
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#include "../utils/common.hpp"
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/* 生成一个数组，元素为 { 1, 2, ..., n }，顺序被打乱 */
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vector<int> randomNumbers(int n) {
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vector<int> nums(n);
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// 生成数组 nums = { 1, 2, 3, ..., n }
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for (int i = 0; i < n; i++) {
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nums[i] = i + 1;
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}
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// 使用系统时间生成随机种子
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unsigned seed = chrono::system_clock::now().time_since_epoch().count();
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// 随机打乱数组元素
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shuffle(nums.begin(), nums.end(), default_random_engine(seed));
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return nums;
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}
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/* 查找数组 nums 中数字 1 所在索引 */
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int findOne(vector<int> &nums) {
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for (int i = 0; i < nums.size(); i++) {
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// 当元素 1 在数组头部时，达到最佳时间复杂度 O(1)
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// 当元素 1 在数组尾部时，达到最差时间复杂度 O(n)
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if (nums[i] == 1)
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return i;
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}
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return -1;
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}
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/* Driver Code */
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int main() {
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for (int i = 0; i < 1000; i++) {
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int n = 100;
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vector<int> nums = randomNumbers(n);
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int index = findOne(nums);
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cout << "\n数组 [ 1, 2, ..., n ] 被打乱后 = ";
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printVector(nums);
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cout << "数字 1 的索引为 " << index << endl;
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}
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return 0;
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}
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