学习map和hash_map

练习代码：

#include <stdlib.h>
#include <hash_map>
#include <map>
#include <string>
using namespace std;

struct cmp
{
    // 重载operator()
    // 注意：compare函数的参数必须写成const类型，否则无法编译通过
    // 这里是有意使string按字典序的反序排列
    bool operator()(const string& str1, const string& str2)
    {
        return str1>str2;
    }
};


int main()
{
    printf(">> map:
");
    // 基于RB-Tree的map
    // 能自动排序，快速检索、删除、插入
    map<string, int, cmp> m;
    m.insert(make_pair(string("Clark"), 12));
    m.insert(make_pair(string("Jone"), 8));
    m.insert(make_pair(string("Ada"), 1));
    m.insert(make_pair(string("Lee"), 5));
    m[string("Jack")]++;
    m[string("Sam")] = m[string("Mike")] + 2;

    // 重复插入无效
    m.insert(make_pair(string("Lee"), 8));

    map<string, int, cmp>::iterator iter;

    // map的检索时间复杂度为O(lnN)
    iter = m.find(string("Mike"));
    if (iter != m.end())
    {
        printf("Found Mike !
");
        m.erase(string("Mike"));
        printf("Deleted Mike !
");
    }

    printf(">> One by one :
");
    for (iter = m.begin(); iter != m.end(); iter++)
        printf("Key=%s, Value=%d
", iter->first.c_str(), iter->second);
    
    printf(">> hash_map:
");
    // 基于hash_table的hash_map
    // 能快速减速、删除、插入，不能排序
    hash_map<string, int> h_m;
    h_m.insert(make_pair(string("Clark"), 12));
    h_m.insert(make_pair(string("Jone"), 8));
    h_m.insert(make_pair(string("Ada"), 1));
    h_m.insert(make_pair(string("Lee"), 5));
    h_m[string("Jack")]++;
    h_m[string("Sam")] = h_m[string("Mike")] + 2;

    // 重复插入无效
    h_m.insert(make_pair(string("Lee"), 8));
    
    hash_map<string, int>::iterator h_iter;

    // hash_map的检索时间复杂度为O(1)，优于RB-Tree的map
    h_iter = h_m.find("Mike");
    if (h_iter != h_m.end())
    {
        printf("Found Mike !
");
        h_m.erase(string("Mike"));
        printf("Deleted Mike !
");
    }

    printf(">> One by one :
");
    for (h_iter = h_m.begin(); h_iter != h_m.end(); h_iter++)
        printf("Key=%s, Value=%d
", h_iter->first.c_str(), h_iter->second);

    system("pause");
    return 0;
}

输出结果：

>> map:
Found Mike !
Deleted Mike !
>> One by one :
Key=Sam, Value=2
Key=Lee, Value=5
Key=Jone, Value=8
Key=Jack, Value=1
Key=Clark, Value=12
Key=Ada, Value=1
>> hash_map:
Found Mike !
Deleted Mike !
>> One by one :
Key=Clark, Value=12
Key=Sam, Value=2
Key=Jone, Value=8
Key=Lee, Value=5
Key=Ada, Value=1
Key=Jack, Value=1
请按任意键继续. . .