priority_queue为复合结构排序：
1 #include <iostream> 2 #include <queue> 3 4 using namespace std; 5 struct Node{ 6 int x; 7 string y; 8 Node( int a= 0, string b = "" ): 9 x(a), y(b) {} 10 }; 11 bool operator<( Node a, Node b ){ // 注意这里的顺序和sort()里面的谓词函数不一样！ 12 // bool为真的 优先级小 13 if( a.x == b.x ) return a.y < b.y; 14 return a.x < b.x; 15 } 16 //自定义重载小于操作符 17 int main(){ 18 /******************************************** 19 对于自定义类型，则必须自己重载 operator< 20 自定义类型重载 operator< 后，声明对象时就可以只带一个模板参数。 21 看下面的例子 22 *******************************************/ 23 24 cout<<"自定义： "<<endl; 25 priority_queue<Node> q2; 26 priority_queue<int> q3; 27 std::string tmp = ""; 28 29 for( int i= 10; i>0; --i ){ 30 tmp = tmp + "12"; 31 q2.push( Node(i, tmp) ); 32 q3.push(i); 33 } 34 while( !q2.empty() ){ 35 cout << q2.top().x << ' ' << q2.top().y << endl; 36 q2.pop(); 37 } 38 while( !q3.empty() ){ 39 cout << "q3 output: "<<q3.top() << endl; 40 q3.pop(); 41 } 42 //注意上面不能这样来定义：priority_queue<Node, vector<Node>, greater<Node> >; 43 //这样定义是错误的！！！！ 44 //原因是：greater<node>没有定义 45 46 //必须定义如下函数对象，才能这样定义： 47 // priority_queue<Node, vector<Node>, cmp >; 48 /* 49 struct cmp{ 50 bool operator() ( Node a, Node b ){ 51 if( a.x== b.x ) return a.y> b.y; 52 53 return a.x> b.x; } 54 }; 55 */ 56 return 0; 57 } 58 59 root@u18:~/cp/test# g++ priority.cpp -g -Wall 60 root@u18:~/cp/test# valgrind --tool=memcheck --leak-check=yes ./a.out 61 ==24385== Memcheck, a memory error detector 62 ==24385== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al. 63 ==24385== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info 64 ==24385== Command: ./a.out 65 ==24385== 66 自定义： 67 10 12 68 9 1212 69 8 121212 70 7 12121212 71 6 1212121212 72 5 121212121212 73 4 12121212121212 74 3 1212121212121212 75 2 121212121212121212 76 1 12121212121212121212 77 q3 output: 10 78 q3 output: 9 79 q3 output: 8 80 q3 output: 7 81 q3 output: 6 82 q3 output: 5 83 q3 output: 4 84 q3 output: 3 85 q3 output: 2 86 q3 output: 1 87 ==24385== 88 ==24385== HEAP SUMMARY: 89 ==24385== in use at exit: 0 bytes in 0 blocks 90 ==24385== total heap usage: 20 allocs, 20 frees, 1,012 bytes allocated 91 ==24385== 92 ==24385== All heap blocks were freed -- no leaks are possible 93 ==24385== 94 ==24385== For counts of detected and suppressed errors, rerun with: -v 95 ==24385== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2)
