lambda表达式

sort函数使用lambda表达式

priority_queue使用lambda表达式

求数组中第K个最大元素 最小堆

class Solution {
public:
    int findKthLargest(vector<int>& nums, int k) {
        int n = nums.size();
        auto cmp=[](int a,int b){return a>b;};
        priority_queue<int,vector<int>,decltype(cmp)> pq(cmp);
        for(int i = 0; i < n; i ++){
            if(pq.size()<k){pq.push(nums[i]);}
            else if(pq.top()<nums[i]){pq.pop();pq.push(nums[i]);}
        }
        return pq.top();
    }
};

求数组中第K大的元素 最大堆

class KthLargest {
private:
    int k;
    priority_queue<int,vector<int>,greater<int>> pq;
public:
    KthLargest(int k, vector<int>& nums) {
        this->k = k;
        int n = nums.size();
        for(int i = 0; i < n; i ++){
            if(pq.size()<k){pq.push(nums[i]);}
            else if(pq.top()<nums[i]){pq.pop();pq.push(nums[i]);}
        }
    }

    int add(int val) {
        if(pq.size()<this->k){pq.push(val);}
        else if(pq.top()<val){pq.pop();pq.push(val);}
        return pq.top();
    }
};

class KthLargest {
    struct cmp{
        bool operator ()(int &x,int &y){
            return x>y;
        }
    };
private:
    int k;
    priority_queue<int,vector<int>,KthLargest::cmp> pq;
public:
    KthLargest(int k, vector<int>& nums) {
        this->k = k;
        int n = nums.size();
        for(int i = 0; i < n; i ++){
            if(pq.size()<k){pq.push(nums[i]);}
            else if(pq.top()<nums[i]){pq.pop();pq.push(nums[i]);}
        }
    }

    int add(int val) {
        if(pq.size()<this->k){pq.push(val);}
        else if(pq.top()<val){pq.pop();pq.push(val);}
        return pq.top();
    }
};