@YipCubed/

# leet-power-of-3

## No description

Files
• main.cpp
main.cpp
```1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
```
```#include <cstring>
#include <climits>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <cmath>

using namespace std;

// Live coding problems, watch at
// https://www.twitch.tv/yipcubed
//

// makes code faster, but larger. Just for LeetCode fun!
#pragma GCC optimise ("Ofast")

// makes stdin not synced so it is faster. Just for LeetCode fun!
static auto x = [](){ios_base::sync_with_stdio(false); cin.tie(NULL); return NULL;}();

class Solution {
public:
// no looping
// pow(3, 19) is largest 3^x that is less than Max_INT
bool isPowerOfThree(int n) {
return n > 0 &&
static_cast<int>(pow(3, 19)) % n == 0;
}

//  faster than 97.67%
bool isPowerOfThreeOld(int n) {
if (n == 0) return false;
while (n % 3 == 0)
n /= 3;
return n == 1;
}
};

void test1() {
Solution S;
cout << boolalpha;
cout << "27t? " << S.isPowerOfThree(27) << endl;
cout << "28f? " << S.isPowerOfThree(28) << endl;
cout << "9t? " << S.isPowerOfThree(9) << endl;
cout << "45f? " << S.isPowerOfThree(45) << endl;
}

void test2() {
Solution S;
}

void test3() {
Solution S;
}

int main() {
test1();
test2();
test3();
cout << "Done!" << endl;

return 0;
}

```