STL库与pb_ds库简单应用

前者不开O2时谨慎使用！

后者尽量不要用！

STL库介绍比较多，其中字符串库用的比较少但也应该记住

http://www.cnblogs.com/rvalue/p/7276883.html

http://www.cnblogs.com/rvalue/p/7327293.html

pb_ds差别不大，但这两个库最大的缺陷就是几乎无法用gdb调试，只能手工输出

下面这个程序运行出来之后就是个小教程

#include<cstdio>
#include<vector>
#include<ext/pb_ds/priority_queue.hpp>
#include<ext/pb_ds/assoc_container.hpp>

struct Cmp{
    int operator() (const int &a,const int &b) { return a>b; }
};

using namespace std;
using namespace __gnu_pbds;
typedef __gnu_pbds::priority_queue<int,Cmp,pairing_heap_tag > Que;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> Tree;

Que a,d;
Que::point_iterator p=a.push(0);
Tree b,c;
Tree::const_iterator it;

int main(){

    puts("");
    puts("---------using namespace __gnu_pbds---------");
    puts("");

    puts("---Include<ext/pb_ds/assoc_container.hpp> for ‘tree‘---");
    puts("");

    it=b.insert(200).first;
    puts("Insert(int x) returns pair<iterator,bool>");
    printf("b.insert(200).first:%d\n\n",*it);

    b.insert(100);
    puts("Find_by_order(int x) returns the x+1 least element const_iterator");
    printf("b(100,200).find_by_order(1):%d\n\n",*b.find_by_order(1));

    puts("Order_of_key(int x) returns the rank-1 of element‘x‘");
    printf("b(100,200).order_of_key(100):%d\n\n",b.order_of_key(100));

    b.split(100,c);
    puts("Split(int key,Tree C)clear C at first,and move the element larger than key into C");
    printf("b(100,200).split(100,c),     c.begin():%d\n\n",*c.begin());

    puts("---Include<.../priority_queue.hpp> for ‘priority_queue‘---");
    puts("");

    puts("push(int x) returns the inserted point_iterator");
    printf("a.push(0) , *p=*a.push(0):%d\n\n",*p);

    a.push(1); a.push(3); a.modify(p,2);
    puts("Modify(iterator,int) change the value of (*p),this heap is maintained automatically");
    printf("a.modify(p,2) , *p:%d\n\n",*p);

    a.erase(p);
    puts("Erase(iterator) delete this element,this iterator dies");
    printf("a.erase(p) , a.top():%d\n",a.top());
    a.pop(); printf("a.pop() , a.top():%d\n\n",a.top());

    d.push(-1); a.join(d);
    puts("a.join(d) join d into a , and then maintain a,clear d");
    printf("d.push(-1) , a.join(d) ,a.top():%d\n\n",a.top());

    puts("----Other functions are not normally used in contests----");
    return 0;
}

三份比较好的教程

https://gitee.com/HocRiser/templates/blob/master/Others/C_ext_pb_ds_1.pdf

https://gitee.com/HocRiser/templates/blob/master/Others/C_ext_pb_ds_2.pdf

https://gitee.com/HocRiser/templates/blob/master/Others/STL.pdf

没有这方面的例题，万不得已的时候才会用

上面有篇文章中说经测试一般不慢于STL库，但实测有不少情况下常数有STL的三倍之多。

且考场上是否允许使用仍有争议（NOI2017现场有人用没出事但不代表其他考试一定没事）

原文地址：https://www.cnblogs.com/HocRiser/p/8178619.html