字符串相乘leetcode

转自leetcode的一位作者：

public String multiply(String num1, String num2) {
          
        int n1 = num1.length()-1;
        int n2 = num2.length()-1;
        if(n1 < 0 || n2 < 0) return "";
        int[] mul = new int[n1+n2+2];
        
        for(int i = n1; i >= 0; --i) {
            for(int j = n2; j >= 0; --j) {
                int bitmul = (num1.charAt(i)-'0') * (num2.charAt(j)-'0');      
                bitmul += mul[i+j+1]; // 先加低位判断是否有新的进位
                
                mul[i+j] += bitmul / 10;
                mul[i+j+1] = bitmul % 10;
            }
        }
        
        StringBuilder sb = new StringBuilder();
        int i = 0;
        // 去掉前导0
        while(i < mul.length-1 && mul[i] == 0) 
            i++;
        for(; i < mul.length; ++i)
            sb.append(mul[i]);
        return sb.toString();
    }

来源：CSDN

作者：azago

链接：https://blog.csdn.net/cjm083121/article/details/90674314