写写我的大数乘法

课题还是没有想好，便重新看了Algorithms(2006)，大数乘法一直没有自己实现过，就写了写，仅仅是整数的实现：
PS:书籍还是看原版的好，被逼的无奈看了英文原版的ALGORITHMS，自己的看法是原版认识的单词必然会少一点，但理解作者的思想要比较容易，能得到更多启发。我之前也是怕原版，看了几行就想换中文的，其实读英文远没有想象的那么难，只要开了头，后面跟看中文差别不是很大。各位还是努力看看原版吧，会有不同收获的。

#include<iostream>using namespace std;#define MAX_mulf 100#define MAX_muls 100#define MAX_result 500int similar_binary(int ,int);int judge_num(int num[],int n);int move_matrix_left(int num[],int n,int max);void matrix_multiply_num(int num[],int para);void matrix_multiply_matrix(int faced[],int mutiply[]);void matrix_add_matrix(int first[],int second[]);void copy_arr(int result[],int source[],int lenth);void out_put(int num[],int max);void transfer_char_num(char mul[],int num[]);int main(){int test[MAX_mulf];int prepare[MAX_muls];memset(test,0,sizeof(test));memset(prepare,0,sizeof(prepare));char multia[MAX_mulf];char multib[MAX_muls];printf("please input two big numbers seperated by the space key: \n");scanf("%s %s",multia,multib);transfer_char_num(multia,test);//out_put(test,MAX_mulf);transfer_char_num(multib,prepare);//out_put(prepare,MAX_muls);matrix_multiply_matrix(test,prepare);system("pause");return 1;}/* output the array to judge */void out_put(int num[],int max){int i = judge_num(num,max);i--;while(i >=0){cout<<num[i];i--;}cout<<endl;}/* judge the lenth of the array */int judge_num(int num[],int n){int i = n-1;while(num[i] == 0){i--;}i++;return i;}/* from char to num */void transfer_char_num(char mul[],int num[]){int i = 0;int count = 0;while(mul[i] != '\0'){i++;}count = i;count--;i = 0;while(i<=count){num[i] = mul[count-i] - '0';i++;}}/* move array right ---- move number left */int move_matrix_left(int num[],int n,int max){int head = judge_num(num,max);head--;if(head+n>=max)return 0;while(head >=  0){num[head+n] = num[head];head--;}n = n-1;while(n >= 0){num[n] = 0;n--;}}/* copy one array to another */void copy_arr(int result[],int source[],int lenth){lenth--;while(lenth >= 0){result[lenth] = source[lenth];lenth--;}}void matrix_multiply_num(int num[],int para){int i = judge_num(num,MAX_mulf);i--;int temp;int up_position = 0;for(int j=0; j<=i;j++){num[j] = num[j] * para;num[j] += up_position;temp = num[j];num[j] = temp%10;up_position = temp/10;}}/* compared to the demical addition */void matrix_add_matrix(int first[],int second[]){int end_first = judge_num(first,MAX_mulf) - 1;int end_second = judge_num(second,MAX_muls) - 1;int up_position = 0;int last;int flag = 0;int temp;if(end_first>end_second){last = end_second;flag = 1;}else{last = end_first;}for(int i=0;i<=last;i++){first[i] += second[i];first[i] += up_position;temp = first[i];first[i] = temp%10;up_position = temp/10;}if(!flag)for(int i=last+1;i<=end_second;i++)first[i] = second[i];  int i = last+1;   for(;;i++){first[i] += up_position;if(first[i]>9){temp = first[i];first[i] = temp%10;up_position = temp/10;}elsebreak;    }}void matrix_multiply_matrix(int faced[],int mutiply[]){int result[MAX_result];memset(result,0,sizeof(result));int temp[MAX_mulf];memset(temp,0,sizeof(temp));int end_first = judge_num(faced,MAX_mulf) - 1;int end_second = judge_num(mutiply,MAX_muls) - 1;int head = end_second;while(head >= 0){if(head<end_second)move_matrix_left(result,1,MAX_mulf);if(mutiply[head] != 0){int  num_deal = mutiply[head];copy_arr(temp,faced,end_first);matrix_multiply_num(temp,mutiply[head]);matrix_add_matrix(result,temp);}head--;}out_put(result,MAX_result);}/*int similar_binary( int width, int height){if(height == 0)return 0;else{      int z;  z =similar_binary(width,height>>1);z = 2*z;if(height&1)z+=width;return z;}}*/