回文数（内含高精度加法，字符串是否为回文的判断）

Posted 2021-03-06 es-war

 

 

 

#include<iostream>
#include<string>
using namespace std;

const int Max = 550;
int Compare(int a[], int b[]); 
void Plus(int a[], int b[], int n); 
void Insert(int a[], int b[]);

int main()
{
    int a[Max] = {0}, b[Max] = {0}, step = 0, n;
    string str1;
    cin >> n >> str1;
    int len = str1.size(), i;
    a[0] = len;
    for (i = 1; i <= len; i ++)
      {
          if (str1[len - i] >= ‘A‘ && str1[len - i] <= ‘F‘)
            a[i] = str1[len - i] - ‘A‘ + 10;
          else
            a[i] = str1[len - i] - ‘0‘;
      }
    Insert(a, b);
    for(step = 0 ; step <= 30; step ++)
    {
        if (Compare(a, b) == 0)
          break;
        Plus(a, b, n);
        Insert(a, b);
    }
    if (step > 30)
      cout << "NO";
    else
      cout <<"STEP=" << step << endl;
    return 0;
} 

int Compare(int a[], int b[])
{
    int i;
    for (i = a[0]; i > 0; i --)
    {
        if (a[i] > b[i])
          return 1;
        else if (a[i] < b[i])
          return -1;
    }
    return 0; 
}

void Plus(int a[], int b[], int n)
{
    int i, len = a[0];
    for (i = 1; i <= len; i ++)
    {
        a[i] = a[i] + b[i];
        a[i + 1] += a[i] / n;
        a[i] = a[i] % n;
    }
    if (a[len + 1] != 0)  //最高位进位 
      a[0] ++;
}

void Insert(int a[], int b[])
{
    int i, len = a[0];
    b[0] = len;
    for (i = 1; i <= len; i ++)
      b[i] = a[len - i + 1];
}