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T107.java
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45 lines (41 loc) · 1.42 KB
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/**
* @Author:Aliyang
* @Data: Created in 下午1:42 18-6-14
* multiply-strings：我的解法
* 思路：字符串模拟乘法
**/
public class T107 {
public String multiply(String num1, String num2) {
if (num1==null||num2==null)
return "";
int[] middle=new int[num1.length()+num2.length()];//中间数组,循环结束即为结果数组
int i=0,j=0;
for (i=num1.length()-1;i>=0;i--){
int jinwei=0;//进位数
for (j=num2.length()-1;j>=0;j--){
int tmp=Integer.valueOf(num1.charAt(i)-'0')*Integer.valueOf(num2.charAt(j)-'0');
int tmp_jinwei=jinwei;
jinwei=(middle[i+j+1]+tmp+jinwei)/10;//更新进位数
middle[i+j+1]=(middle[i+j+1]+tmp+tmp_jinwei)%10;//更新中间数组
}
if (jinwei!=0)
middle[i+j+1]=jinwei;
}
i=0;
while (i<middle.length&&middle[i]==0)//找到非0的i的位置，目的是去掉前面没用的0
i++;
if (i>=middle.length)
return "0";
StringBuilder sb=new StringBuilder();
for (j=middle.length-1;j>=i;j--)
sb.append(middle[j]);
sb.reverse();
return sb.toString();
}
public static void main(String[] args){
T107 t=new T107();
String num1="0";
String num2="0";
System.out.println(t.multiply(num1,num2));
}
}