set查找和统计示例

#include <iostream>
#include <set>
using namespace std;int main() {set<int> data = {10, 20, 30, 40, 50, 60, 70, 80, 90, 100};cout << "=== 查找操作详解 ===" << endl;// 1. find() - 精确查找auto it = data.find(50);if(it != data.end()) {cout << "找到50: " << *it << endl;} else {cout << "未找到50" << endl;}// 查找不存在的元素it = data.find(55);if(it == data.end()) {cout << "未找到55" << endl;}// 2. count() - 统计出现次数（set中只能是0或1）cout << "50出现次数: " << data.count(50) << endl;cout << "55出现次数: " << data.count(55) << endl;// 3. contains() - C++20 检查包含关系// if(data.contains(60)) { cout << "包含60" << endl; }
    cout << "\n=== 边界查找 ===" << endl;// 4. lower_bound() - 第一个 >= 的值// 5. upper_bound() - 第一个 > 的值// 6. equal_range() - [lower_bound, upper_bound) 的范围int searchValue = 45;auto lower = data.lower_bound(searchValue);auto upper = data.upper_bound(searchValue);cout << "搜索值: " << searchValue << endl;if(lower != data.end()) {cout << "lower_bound: " << *lower << " (第一个>=45的值)" << endl;}if(upper != data.end()) {cout << "upper_bound: " << *upper << " (第一个>45的值)" << endl;}// 使用边界查找实现范围查询cout << "\n范围查询 [30, 70]:" << endl;auto range_start = data.lower_bound(30);auto range_end = data.upper_bound(70);for(auto it = range_start; it != range_end; ++it) {cout << *it << " ";}cout << endl;return 0;
}