C++学习：第四章数据结构和算法 - （五）算法基础、二分法查找

示例代码

#include <iostream>
#include <string>
#include <ctime>
#include <algorithm>//这个可以省略，但是安全起见要写上
using namespace std;

class Person{
	string name;
	int age;
	string addr;
public:
	Person(const char* n, int a, const char* ad)
		:name(n),age(a),addr(ad){}
	friend bool operator < (const Person& a, const Person b){
		return a.name < b.name;
	}
	friend bool operator == (const Person& a, const Person b){
		return a.name == b.name;
	}
	friend ostream& operator << (ostream& o, const Person& a){
		o << a.name << "; " << a.age << "; " << a.addr << endl;
		return o;
	}
};

// 二分法查找
Person* binarySearch(Person* a, int n, const string& name){
	if (n<=0){
		return NULL;
	}
	Person t(name.c_str(), 0, "");
	int mid = n/2;
	if (a[mid] ==t){
		return a+mid;
	}
	if (t<a[mid]){
		return binarySearch(a, mid, name);
	}
	return binarySearch(a+mid+1, n-(mid+1), name);
}

Person* binarySearch2(Person* a, int n, const string& name){
	
	int b=0, e = n-1;
	Person t(name.c_str(), 0, "");
	while(b<=e){
		int mid = (b+e)/2;
		if(a[mid]==t)
			return a+mid;
		if(t<a[mid])
			e = mid-1;
		else
			b = mid+1;
	}
}


//冒泡排序
void sort(int*a , int n){
	bool changed;
	do{
		changed = false;
		for(int i=1; i<n; i++){
			if (a[i]<a[i-1]){
				swap(a[i], a[i-1]);
				changed = true;
			}
		}
	}while(changed);
}

int main (){
	Person a[5] = {
		Person("kaskk", 34, "lksjalkd"),
		Person("asda", 22, "dfs"),
		Person("sdfhd", 55, "sdfb"),
		Person("mdjsj", 50, "asghjkjhg"),
		Person("dfs", 14, "wewqr")
	};
	for (int i=0; i<5; i++){
		for(int j=i+1; j<5; j++){
			if(a[j]<a[i]){
				swap(a[j], a[i]);
			}
		}
	}
	for(int i=0; i<5; i++)
		cout << a[i] ;

	//cpu时间
	clock_t t1 = clock();
	cout << *binarySearch(a, 5, "dfs");
	cout << *binarySearch2(a, 5, "dfs");
	clock_t t2 = clock();
	cout << double(t2 - t1)/CLOCKS_PER_SEC;
	getchar();
	return 0;
}