[数据结构与算法]每日一练防手生

将一个正整数分解质因数。例如：输入90,打印出90=2*3*3*5。

public class PrimeFactorDemo {
?? ?private final static int START_FACTOR = 2;

?? ?public void printPrimeFactor(int i) {
?? ??? ?int factor = START_FACTOR;
?? ??? ?System.out.print(i + "=");
?? ??? ?int leftNum = i;
?? ??? ?while (factor <= Math.sqrt(leftNum)) {
?? ??? ??? ?if (leftNum % factor == 0) {
?? ??? ??? ??? ?leftNum = leftNum / factor;
?? ??? ??? ??? ?System.out.print(factor + "*");
?? ??? ??? ??? ?factor = START_FACTOR;
?? ??? ??? ??? ?continue;
?? ??? ??? ?} else {
?? ??? ??? ??? ?factor++;
?? ??? ??? ?}
?? ??? ?}
?? ??? ?if (leftNum < i) {
?? ??? ??? ?System.out.print(leftNum);
?? ??? ?} else {
?? ??? ??? ?System.out.println("不可分解质因数");
?? ??? ?}
?? ?}

?? ?public static void main(String[] args) {
?? ??? ?PrimeFactorDemo demo = new PrimeFactorDemo();
?? ??? ?demo.printPrimeFactor(90);
?? ?}
}