题解 | 小红的方神题spj

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

int main() {
    int n;
    cin >> n;
    vector<long long> a(n);
    for (auto &x : a) cin >> x;

    for (int i = n; i > 1; --i) {
        for (int j = 0; j < i - 1; ++j) {
            a[j] = abs(a[j] - a[j + 1]);
        }
    }

    cout << a[0] << '\n';
    return 0;
}