算法大数整数相加

大数整数加法

#include <iostream>

#include <iomanip>

#include <string.h>

#include <string>

#include <algorithm>

#include <stdio.h>

#include <malloc.h>

#include <stdlib.h>

#include <cmath>

using namespace std;

 

#define MAXN 1000

 

int a[MAXN],b[MAXN];

 

int main(int argc, const char * argv[])

{

   string str1,str2;//保存输入

   long int len1,len2;

   long int i,j,k;

   int up;

 

   /*输入流程*/

   while(cin>>str1>>str2) {

   if(str1[0] == '0' && str2[0] == '0')

       break;

   /*初始化各量*/

   len1 = str1.length();

   len2 = str2.length();

   memset(a, 0, sizeof(a));

   memset(b, 0, sizeof(b));

 

   /*注意，必须倒着保存数据*/

   for (i = len1 - 1, k = 0; i != -1; -- i)

   {

       a[k] = str1[i] - '0';

       k++;

   }

   for (j = len2 - 1, k = 0; j != -1; -- j)

   {

       b[k] = str2[j] - '0';

       k++;

   }

   for (i = 0, up = 0; i < MAXN; ++ i)

   {

       a[i] = a[i] + b[i] + up;

       up = a[i] / 10;

       a[i] %= 10;

   }

   for (i = MAXN - 1; i != -1; -- i)

   {

       if (a[i])

       {

           break;

       }

   }

   for (k = i; k != -1; --k)

   {

       cout<<a[k];

   }

   cout << endl;

   }

   return 0;

}

 

分析

用两个字符串型的数组倒着存数字，