UVA-202 循环小数 题解答案代码 算法竞赛入门经典第二版

使用数组存储每次的余数和商，当余数和商都与之前存储的相同时，说明找到了循环节

#include<cstdio>

#define MAXN 1000000
int arr[MAXN];
int chu[MAXN];

int main() {
  int a,b,m,n,i,j,k;
  int cyc;
  bool flag;
  while(scanf("%d %d", &a, &b) == 2) {
    if(b == 0)
      continue;
    m = a, n = b;
    i = -1;
    flag = false;
    a %= b;
    a *=10;
    while(i < MAXN) {
      if(a == 0)
      {
        ++i;
        arr[i] = 0;
        arr[i+1] = 0;
        chu[i] = 0;
        chu[i+1] = 0;
        ++i;
        cyc = 1;
        break;
      }
      for(j=0;j<i;++j) {
        if(chu[i] == chu[j] && arr[i] == arr[j])
        {
          cyc = i-j;
          flag = true;
          break;
        }
      }
      if(flag == true)
        break;
      ++i;
      arr[i] = a/b;
      a %= b;
      chu[i] = a;
      if(a < b) {
        a *= 10;
      }
    }
    printf("%d/%d = %d.", m, n, m/n);
    for(j=0;j<(i-cyc);++j) 
      printf("%d",arr[j]);
    putchar('(');
    for(j=0;j<cyc && j<50;++j)
      printf("%d",arr[j+i-cyc]);
    if(cyc > 50)
      printf("...");
    puts(")");
    /*
    for(j=0;j<=i;++j)
      printf("[%d %d]",arr[j], chu[j]);
    puts("");
    */
    printf("   %d = number of digits in repeating cycle\n\n", cyc);
  }

  return 0;
}