标签:map set return string long include buf unordered target
关于set和map的区别前面已经说过,这里仅是用hashtable将其实现,所以不做过多说明,直接看程序
unordered_set
#include<stdexcept> #include<string> #include<cstdlib> #include<cstdio> #include<algorithm> #include<iostream> #include<ctime> #include<unordered_set> using namespace std; long get_a_target_long() { long target = 0; cout<<"target(0~"<<RAND_MAX<<"):"; cin>>target; return target; } string get_a_target_string() { long target = 0; char buf[10]; cout<<"target(0~"<<RAND_MAX<<"):"; cin>>target; snprintf(buf, 10, "%ld", target); return string(buf); } int compareLongs(const void* a, const void* b) { return (*(long*)a - *(long*)b); } int compareStrings(const void *a, const void *b) { if(*(string*)a > *(string*)b) return 1; else if(*(string*)a < *(string*)b) return -1; else return 0; } void test_unordered_set(long& value) { cout << "\ntest_unordered_set().......... \n"; unordered_set<string> c; char buf[10]; clock_t timeStart = clock(); for(long i=0; i< value; ++i) { try { snprintf(buf, 10, "%d", rand()); c.insert(string(buf)); } catch(exception& p) { cout << "i=" << i << " " << p.what() << endl; abort(); } } cout << "milli-seconds : " << (clock()-timeStart) << endl; cout << "unordered_set.size()= " << c.size() << endl; //元素个数 cout << "unordered_set.max_size()= " << c.max_size() << endl; // cout << "unordered_set.bucket_count()= " << c.bucket_count() << endl;//篮子个数 cout << "unordered_set.load_factor()= " << c.load_factor() << endl; //负载 cout << "unordered_set.max_load_factor()= " << c.max_load_factor() << endl;//最大负载 cout << "unordered_set.max_bucket_count()= " << c.max_bucket_count() << endl; // for (unsigned i=0; i< 20; ++i) { cout << "bucket #" << i << " has " << c.bucket_size(i) << " elements.\n"; } string target = get_a_target_string(); { timeStart = clock(); auto pItem = find(c.begin(), c.end(), target); //比 c.find(...) 慢很多 cout << "std::find(), milli-seconds : " << (clock()-timeStart) << endl; if (pItem != c.end()) cout << "found, " << *pItem << endl; else cout << "not found! " << endl; } { timeStart = clock(); auto pItem = c.find(target); //比 std::find(...) 快很多 cout << "c.find(), milli-seconds : " << (clock()-timeStart) << endl; if (pItem != c.end()) cout << "found, " << *pItem << endl; else cout << "not found! " << endl; } } int main() { long int value; cout<<"how many elements: "; cin>>value; test_unordered_set(value); return 0; }
运行结果
unordered_map
#include<stdexcept> #include<string> #include<cstdlib> #include<cstdio> #include<algorithm> #include<iostream> #include<ctime> #include<unordered_map> using namespace std; long get_a_target_long() { long target = 0; cout<<"target(0~"<<RAND_MAX<<"):"; cin>>target; return target; } string get_a_target_string() { long target = 0; char buf[10]; cout<<"target(0~"<<RAND_MAX<<"):"; cin>>target; snprintf(buf, 10, "%ld", target); return string(buf); } int compareLongs(const void* a, const void* b) { return (*(long*)a - *(long*)b); } int compareStrings(const void *a, const void *b) { if(*(string*)a > *(string*)b) return 1; else if(*(string*)a < *(string*)b) return -1; else return 0; } void test_unordered_map(long& value) { cout << "\ntest_unordered_map().......... \n"; unordered_map<long, string> c; char buf[10]; clock_t timeStart = clock(); for(long i=0; i< value; ++i) { try { snprintf(buf, 10, "%d", rand()); c[i] = string(buf); //特殊的插入方式 } catch(exception& p) { cout << "i=" << i << " " << p.what() << endl; abort(); } } cout << "milli-seconds : " << (clock()-timeStart) << endl; cout << "unordered_map.size()= " << c.size() << endl; //元素个数 cout << "unordered_map.max_size()= " << c.max_size() << endl; long target = get_a_target_long(); timeStart = clock(); auto pItem = c.find(target);//map 不用 std::find() cout << "c.find(), milli-seconds : " << (clock()-timeStart) << endl; if (pItem != c.end()) cout << "found, value=" << (*pItem).second << endl; else cout << "not found! " << endl; } int main() { long int value; cout<<"how many elements: "; cin>>value; test_unordered_map(value); return 0; }
运行结果
标签:map,set,return,string,long,include,buf,unordered,target 来源: https://www.cnblogs.com/area-h-p/p/12015966.html
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