一、题目内容

二、题解

解法1：

思路

代码

public class Solution {
    public String solve (String s, String t) {
        if(s == null || s.length() == 0 || t == null || t.length() == 0){
            return "0";
        }
        int sl = s.length();
        int tl = t.length();
        // write code here
        StringBuilder longStr = new StringBuilder(sl>tl?s:t).reverse();
        StringBuilder shotStr = new StringBuilder(sl>tl?t:s).reverse();
        int[] nums = new int[sl+tl];
        int c = 0;//进位
        int k = 0;//当前位置
        for(int i = 0;i<shotStr.length();i++){
            c = 0;
            k = i;
            for(int j = 0;j<longStr.length();j++){
                int m = shotStr.charAt(i)-'0';
                int n = longStr.charAt(j)-'0';
                int curRes = m*n+c+nums[k];
                nums[k] = curRes % 10;
                c = curRes / 10;
                k++;
            }
            nums[k]+= c;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < nums.length; i++) {
            sb.append(nums[i]);
        }
        String res = sb.reverse().toString();
        if (res.charAt(0)=='0'){
            return res.substring(1);
        }else {
            return res;
        }
    }
}