C语言入门-leetcode练习之第43题字符串相乘.zip

#include <stdio.h> #include <stdlib.h> #include <string.h> static char* multiply(char* num1, char* num2) { if (*num1 == '\0') { return num1; } if (*num2 == '\0') { return num2; } int i, j; int len1 = strlen(num1); int len2 = strlen(num2); char *result = malloc(len1 + len2 + 1); memset(result, '0', len1 + len2 + 1); result[len1 + len2] = '\0'; for (i = len2 - 1; i >= 0; i--) { int carry = 0; for (j = len1 - 1; j >= 0; j--) { carry += (num2[i] - '0') * (num1[j] - '0') + (result[i + j + 1] - '0'); result[i + j + 1] = carry % 10 + '0'; carry /= 10; } result[i + j + 1] = carry + '0'; } while (result[0] == '0' && result[1] != '\0') { result++; } return result; } int main(int argc, char **argv) { if (argc != 3) { fprintf(stderr, "Usage: ./test m1 m2\n"); exit(-1); } printf("%s\n", multiply(argv[1], argv[2])); return 0; }