queue vs priority_queue

//头文件
#include<queue>01 queue< T > q; bool q.empty()void q.push( const T& value );void q.pop();size_t q.size();T& q.front();       //T& q.back();        //02 priority_queue< T,C<T>,cmpS > q;// 无 ()priority_queue< T,vector<T>,greater<T> > q;// 小顶堆bool q.empty()void q.push( const T& value );void q.pop();size_t q.size();T& q.top()          // diff_op