STL-related

STL/STL-priority_queue/main.cpp

@@ -0,0 +1,43 @@
+#include <queue>
+#include <functional>
+#include <iostream>
+using namespace std;
+
+bool cmp(const int& a, const int& b) {
+    return a < b;
+}
+
+class compare {
+public:
+    template <typename T>
+    bool operator()(const T& a, const T& b) {
+        //返回大的，泛型不能直接返回指针，没有初始化
+        //用struct或者class套一下，在class初始化的过程中就顺带着初始化了
+        return a < b;//false是向上swap
+    }
+};
+
+int main() {
+    auto cmpl = []<class T>(const T& a, const T& b) {
+        return a < b;
+    };
+    //priority_queue<int, deque<int>, decltype(cmpl)> pq(cmpl);合法
+    //priority_queue<int, deque<int>, bool(*)(const int&, const int&)> pq(cmp);合法
+    priority_queue<int, deque<int>, compare> pq;
+    //上面三种写法非常重要
+    pq.push(1);
+    pq.push(2);
+    pq.push(6);
+    pq.push(3);
+    pq.push(7);
+    pq.push(4);
+    while (!pq.empty()) {
+        cout << pq.top() << " ";
+        pq.pop();
+    }
+    cout << endl;
+    return 0;
+}
+/*
+7 6 4 3 2 1
+ */