题解 | 小苯的麦克斯

#include <iostream>
#include <vector>
using namespace std;

int findmax(vector<int>& a, int l, int r) {
    int maxa = a[l];
    for (int i = l; i <= r; i++) {
        if (maxa < a[i]) {
            maxa = a[i];
        }
    }
    return maxa;
}

int solution(vector<int>& a, int n) {
    int a_max = findmax(a, 1, n);
    int cnt = 0;
    int ref = 0;
    for (int i = 1; i <= n; i++) {
        if (a[i] == a_max) {
            cnt++;
            if (a[i - 1] != 0 || a[i + 1] != 0) {
                break;
            } else {
                ref++;
            }
        }
    }
    if (cnt == ref) {
        if (a_max == 1) {
            return -1;
        } else {
            return a_max - 1;
        }
    }

    else {
        return a_max;
    }
}

int main() {
    int t;
    cin >> t;
    for (int i = 0; i < t; i++) {
        int n;
        cin >> n;
        vector<int>a(n + 2);
        for (int j = 1; j < n + 1; j++) {
            cin >> a[j];
        }
        a[0] = 0;
        a[n + 1] = 0;
        int result = solution(a, n);
        cout << result << endl;
    }
}
// 64 位输出请用 printf("%lld")