Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string.
Input: num1 = "123", num2 = "456" Output: "56088"
字符串相乘。
解决：
1、n位和m位数字相乘，乘积result不超过m+n位。
2、其中，num1[i] * num2[j] 影响的是 result[i+j+1]
1 class Solution { 2 public: 3 string multiply(string num1, string num2) { 4 if (num1 == "0" || num2 == "0") 5 return "0"; 6 int len1 = num1.size(); 7 int len2 = num2.size(); 8 vector<int> v(len1 + len2, 0); 9 int carry = 0; 10 for (int i=len1-1; i>=0; --i) { 11 carry = 0; 12 for (int j=len2-1; j>=0; --j) { 13 int n1 = num1[i] - ‘0‘; 14 int n2 = num2[j] - ‘0‘; 15 v[i+j+1] += n1 * n2 + carry; 16 carry = v[i+j+1] / 10; 17 v[i+j+1] = v[i+j+1] % 10; 18 } 19 if (carry) 20 v[i] += carry; 21 } 22 string mul; 23 if (v[0] != 0) 24 mul += v[0] + ‘0‘; 25 for (int i=1; i<len1+len2; ++i) 26 mul += v[i] + ‘0‘; 27 return mul; 28 } 29 };
原文：https://www.cnblogs.com/Zzz-y/p/9009913.html