c++

排序比较

Node定义

struct Node {
    int time;
    int st; // 1 is up, 0 is down

    Node(int _time, int _st) : time(_time), st(_st) {}
};

class 比较

struct cmp {
    bool operator()(const Node* a, const Node* b) const {
        if (a->time == b->time) return a->st < b->st;
        return a->time < b->time;
    }
};

static 函数比较

static bool cmp(const Node* a, const Node* b) {
    if (a->time == b->time) return a->st < b->st;
    return a->time < b->time;
}

匿名函数

sort(planes.begin(), planes.end(), [](const Node* a, const Node* b) {
    if (a->time == b->time) return a->st < b->st;
    return a->time < b->time;
});

堆

默认大根堆
priority_queue<int, vector<int>> maxHeap;

c++自带比较器
priority_queue<int, vector<int>, greater<int>> minHeap;
priority_queue<int, vector<int>, less<int>> maxHeap;

自定义
小根堆

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

priority_queue<int, vector<int>, cmp> minHeap;

小根堆

struct cmp {
    bool operator() (const int &a, const int &b) {
        return a < b;
    }
};

priority_queue<int, vector<int>, cmp> maxHeap;

代码内部lambda函数自定义比较

unordered_map<char, int> hash;

auto cmp = [&](const char &a, const char &b) {
    return hash[a] < hash[b];
};

priority_queue<char, vector<char>, decltype(cmp)> maxHeap{cmp};