python/TangDou/LanQiaoBei/LanQiaoBeiWhitePaper/6_ThreeNumberCount.cpp

#include <bits/stdc++.h>

using namespace std;
int n, cnt;

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++)//首位不能是0
        for (int j = 0; j <= n; j++)//二位可以是0
            for (int k = 1; k <= n; k += 2) //三位必须是奇数，1，3，5，7，...
                if (k != i && k != j && i != j) cnt++;

    cout << cnt << endl;
    return 0;
}