排序函数

sort() 排序函数

1. 使用lambda表达式进行排序

    vector<int> arr = {4,5,3,8,2,1,6,7};
    sort(arr.begin(), arr.end(), [](int a, int b) {
        return a > b; 
    });
    for (int num : arr) {
        cout << num << " "; //8 7 6 5 4 3 2 1 
    }
    sort(arr.begin(), arr.end(), [](int a, int b) {
        return a < b; 
    });
    for (int num : arr) {
        cout << num << " "; //1 2 3 4 5 6 7 8
    }

2. 使用greater和lesser函数进行排序

    vector<int> arr = {4,5,3,8,2,1,6,7};
    sort(arr.begin(), arr.end(),greater<int>());
    for (int num : arr) {
        cout << num << " "; // 8 7 6 5 4 3 2 1
    }
    cout << endl;
    sort(arr.begin(), arr.end(), less<int>());
    for (int num : arr) {
        cout << num << " "; // 1 2 3 4 5 6 7 8
    }

3. 对结构体进行sort排序

typedef struct node {
    int x,y,z;
    bool operator<(const node& other) const {
        if(this->x==other.x){
            if(this->y==other.y){
                return this->z<other.z;
            }
            return this->y<other.y;
        }
        return this->x<other.x;
    }
    bool operator>(const node& other) const {
        if(this->x==other.x){
            if(this->y==other.y){
                return this->z>other.z;
            }
            return this->y>other.y;
        }
        return this->x>other.x;
    }
} node;
// 不添加greater和lesser函数，默认使用<进行排序
int main(){
    vector<node> arr = {{1, 2, 3}, {1, 2, 4}, {1, 3, 5}, {2, 2, 6}, {2, 3, 7}, {3, 2, 8}};
    sort(arr.begin(), arr.end(), greater<node>());  //使用重载的>进行排序
    for (const node& n : arr) {
        cout << "(" << n.x << " " << n.y << " " << n.z << ") ";
    }
    cout << endl;
    sort(arr.begin(), arr.end(), less<node>()); //使用重载的<进行排序
    for (const node& n : arr) {
        cout << "(" << n.x << " " << n.y << " " << n.z << ") ";
    }
    return 0;
}

4. 对pair进行sort排序

    vector<pair<int, int>> arr = {{1, 2}, {3, 1}, {2, 3}, {4, 0}};
    sort(arr.begin(), arr.end(), [](const pair<int, int>& a, const pair<int, int>& b) {
        return a.first < b.first; // 按照第一个元素升序排序
    });
    for (const auto& p : arr) {
        cout << "(" << p.first << ", " << p.second << ") "; // (1, 2) (2, 3) (3, 1) (4, 0)
    }

5. 对tuple进行sort排序

    vector<tuple<int, int, int>> arr = {{1, 2, 3}, {3, 1, 2}, {2, 3, 1}, {4, 0, 5}};
    sort(arr.begin(), arr.end(), [](const tuple<int, int, int>& a, const tuple<int, int, int>& b) {
        return get<0>(a) < get<0>(b); // 按照第一个元素升序排序
    });
    for (const auto& t : arr) {
        cout << "(" << get<0>(t) << ", " << get<1>(t) << ", " << get<2>(t) << ") "; // (1, 2, 3) (2, 3, 1) (3, 1, 2) (4, 0, 5)
    }