LeetCode_326. Power of Three
2024-08-26 12:48:34
326. Power of Three
Easy
Given an integer, write a function to determine if it is a power of three.
Example 1:
Input: 27
Output: true
Example 2:
Input: 0
Output: false
Example 3:
Input: 9
Output: true
Example 4:
Input: 45
Output: false
Follow up:
Could you do it without using any loop / recursion?
package leetcode.easy;
public class PowerOfThree {
public static void main(String[] args) {
PowerOfThree sol = new PowerOfThree();
int iterations = 1000000; // See table header for this value
long startTime = System.currentTimeMillis(); // 获取开始时间
for (int i = 0; i < iterations; i++) {
sol.isPowerOfThree1(i);
}
long endTime = System.currentTimeMillis(); // 获取结束时间
System.out.println("程序运行时间：" + (endTime - startTime) + "ms"); // 输出程序运行时间
startTime = System.currentTimeMillis(); // 获取开始时间
for (int i = 0; i < iterations; i++) {
sol.isPowerOfThree2(i);
}
endTime = System.currentTimeMillis(); // 获取结束时间
System.out.println("程序运行时间：" + (endTime - startTime) + "ms"); // 输出程序运行时间
startTime = System.currentTimeMillis(); // 获取开始时间
for (int i = 0; i < iterations; i++) {
sol.isPowerOfThree3(i);
}
endTime = System.currentTimeMillis(); // 获取结束时间
System.out.println("程序运行时间：" + (endTime - startTime) + "ms"); // 输出程序运行时间
startTime = System.currentTimeMillis(); // 获取开始时间
for (int i = 0; i < iterations; i++) {
sol.isPowerOfThree4(i);
}
endTime = System.currentTimeMillis(); // 获取结束时间
System.out.println("程序运行时间：" + (endTime - startTime) + "ms"); // 输出程序运行时间
}
public boolean isPowerOfThree1(int n) {
if (n < 1) {
return false;
}
while (n % 3 == 0) {
n /= 3;
}
return n == 1;
}
public boolean isPowerOfThree2(int n) {
return Integer.toString(n, 3).matches("^10*$");
}
public boolean isPowerOfThree3(int n) {
return (Math.log10(n) / Math.log10(3)) % 1 == 0;
}
public boolean isPowerOfThree4(int n) {
return n > 0 && 1162261467 % n == 0;
}
@org.junit.Test
public void test() {
System.out.println(isPowerOfThree1(27));
System.out.println(isPowerOfThree1(0));
System.out.println(isPowerOfThree1(9));
System.out.println(isPowerOfThree1(45));
System.out.println(isPowerOfThree2(27));
System.out.println(isPowerOfThree2(0));
System.out.println(isPowerOfThree2(9));
System.out.println(isPowerOfThree2(45));
System.out.println(isPowerOfThree3(27));
System.out.println(isPowerOfThree3(0));
System.out.println(isPowerOfThree3(9));
System.out.println(isPowerOfThree3(45));
System.out.println(isPowerOfThree4(27));
System.out.println(isPowerOfThree4(0));
System.out.println(isPowerOfThree4(9));
System.out.println(isPowerOfThree4(45));
}
}
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