Python3 解法, 执行用时: 42ms, 内存消耗: 4632K, 提交时间: 2023-01-06 20:52:31

pw = [1 for _ in range(30)]
for i in range(1, 30):
    pw[i] = 3 * pw[i - 1]

def solve():
    n = int(input())
    res = 0
    
    for mask in range((n - 9) // 3, (n - 3) // 3 + 1):
        if mask < 0 or mask & 1:
            continue
        d = n - 3 - 3 * mask
        cnt = bin(mask).count('1')
        for a in range(0, 3):
            for b in range(0, 3):
                c = d - a - b
                if c < 0 or c > 2:
                    continue
                res += n * pw[cnt]
    print(res // 3)

for _ in range(1):solve()

C++(g++ 7.5.0) 解法, 执行用时: 3ms, 内存消耗: 560K, 提交时间: 2022-11-09 16:01:18

#include <bits/stdc++.h>
#define int long long
using namespace std;

int n;

inline int calc(int x) {
	if (x < 0) return 0; x /= 3;
	if (x & 1) return 0; int res = 1;
	while (x) x &= x - 1, res *= 3; return res;
}

signed main() {
	cin >> n; int res = 0;
	for (int i = 0; i < 3; ++i) for (int j = 0; j < 3; ++j)
		res += calc(n - i - j - 3); cout << res * n / 3 << endl;
	return 0;
}

C++(clang++ 11.0.1) 解法, 执行用时: 3ms, 内存消耗: 500K, 提交时间: 2022-11-20 17:03:48

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n;
inline int calc(int x)
{
    if(x<0) return 0;
    x/=3;
    if(x&1) return 0;
    int res=1;
    while(x) x&=x-1,res*=3;return res;
}
signed main()
{
    cin>>n;
    int res=0;
    for(int i=0;i<3;i++)
        for(int j=0;j<3;j++)
            res+=calc(n-i-j-3);
    cout<<res*n/3<<endl;
    return 0;
}

pypy3 解法, 执行用时: 73ms, 内存消耗: 21184K, 提交时间: 2022-11-04 22:03:26

def f(n):
    if n % 2: return 0
    n //= 2
    ans = 1
    for i in range(32):
        if n >> i & 1:
            ans *= 3
    return ans
n = int(input())
ans = 0
for i in range(3):
    for j in range(3):
        for k in range(3):
            x = n - 3 - i - j - k
            if x < 0 or x % 3: continue
            ans += f(x // 3)
print(ans * n // 3)