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