一. 题目
输入数字n,按顺序打印出从1到最大的n位十进制数.比如输入3,则打印出1,2,3一直到最大的3位数即999.
代码请到我的代码库中下载 Point2Offer
二. 代码
package ween_2;
/**难度系数:****
* 剑指offer: 打印1到最大的n位数
* 方法:注意最大数是有多大?(字符串&递归)
* 测试用例:功能测试(正数{121,1,0x7FFFFFFF})
* 特殊输入测试(0,负数)
* @author dingding
* Date:2017-6-22 14:00
* Declaration: All Rights Reserved!
*/
public class No12 {
public static void main(String[] args) {
test1();
test2();
test3();
test4();
}
//solution
private static void print1ToMaxOfNDigits(int n){
if (n<1) {
return;
}
char[] number = new char[n];
for (int i=0;i<10;i++){
number[0] = (char) (i+'0');
print1ToMaxOfNDigitsRecursively(number,n,0);
}
}
//递归
private static void print1ToMaxOfNDigitsRecursively(char[] number, int length, int index) {
if (index == length-1) {
printNumber(number);
return;
}
for (int i=0;i<10;++i){
number[index+1] = (char) (i+'0');
print1ToMaxOfNDigitsRecursively(number, length, index+1);
}
}
//打印字符串,去除前面的0
private static void printNumber(char[] number) {
boolean isBeginning0 = true;
int length = number.length;
for (int i=0;i<length;i++){
if (isBeginning0 && number[i]!='0') {
isBeginning0 = false;
}
if (!isBeginning0) {
System.out.print(number[i]);
}
}
System.out.print("\t");
}
/*==============测试用例===============*/
private static void test1() {
print1ToMaxOfNDigits(1);
System.out.println();
System.out.println("=====================");
}
private static void test2() {
print1ToMaxOfNDigits(0);
System.out.println();
System.out.println("=====================");
}
private static void test3() {
print1ToMaxOfNDigits(-3);
System.out.println();
System.out.println("=====================");
}
private static void test4() {
print1ToMaxOfNDigits(2);
System.out.println();
System.out.println("=====================");
}
}
有不妥当之处,麻烦告知:D