在这里插入代码片//
// Created by xpc on 2023/3/18.
//
#include <iostream>
#include <limits.h>
#include <algorithm>
using namespace std;
/**
 * 查找最大和次大元素，分为3种情况
 * @param a
 * @param low
 * @param high
 * @param maxFirst
 * @param maxSecond
 */
void solve(int a[],int low,int high,int &maxFirst,int &maxSecond) {
    //1.区间中只有一个元素
    if (low==high) {
        maxFirst = a[low];
        //表示无穷小
        maxSecond = INT_MIN;
    }
        //2.区间中只有两个元素
    else if (low==high-1) {
        maxFirst = max(a[low], a[high]);
        maxSecond=min(a[low], a[high]);
    }
        //3.区间有两个以上元素
    else {
        int mid = (low + high) / 2;
        //左区间中求leftMaxFirst和leftMaxSecond
        int leftMaxFirst, leftMaxSecond;
        solve(a, low, mid, leftMaxFirst, leftMaxSecond);
        //右区间中求rightMaxFirst和rightMaxSecond
        int rightMaxFirst, rightMaxSecond;
        solve(a, mid + 1,high, rightMaxFirst, rightMaxSecond);
        if (leftMaxFirst> rightMaxFirst) {
            //leftMaxSecond、rightMaxFirst中求次大元素
            maxFirst = leftMaxFirst;
            maxSecond = max(leftMaxSecond, rightMaxFirst);
        }
        else {
            //leftMaxFirst、rightMaxSecond中求次大元素
            maxFirst = rightMaxFirst;
            maxSecond = max(leftMaxFirst, rightMaxSecond);
        }
    }
}
int main() {
    int n = 0;
    cout << "请输入元素个数" << endl;
    cin >> n;
    int *a = new int[n];
    cout << "请输入元素：" << endl;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    int maxFirst, maxSecond;
    solve(a,0,n-1, maxFirst, maxSecond);
    cout << "最大值为：" << maxFirst<< " " << "次大值为:" << maxSecond << endl;
    system("exit");
}