新手求助一个关于时间函数和scanf输入跳过的问题

#include<stdio.h>
#include<ctype.h>
#include<stdlib.h>
#include<time.h>
#include<stdbool.h>
int main(void)
{
  
  const unsigned int delay=1;
  char play_again='Y';
  int number=0;//user's input;
  int tries=0;//attempt
  int digits=0;// number of digits in sequence
  time_t seed=0;//seed value for random number sequence
  time_t wait_start=0;// stores current time
  bool correct=true;
  int score=0;
  int total_digits=0;
  int game_time=0;
  clock_t start_time=0;
  
  
  printf("\nWelcome to this game, i think you know"
           " the rules,so press enter to play:"
           "remember, number only display %us!",delay);
  scanf("%c",&play_again);
  
  
  do
  {
    //initialize game   
    correct = true;
    tries=0;
    digits=2;
    start_time=clock();
      
    //inner loop for game   
    while(correct)
    {
      ++tries;//a new attempt
      wait_start=clock();
   
      //generate a sequence of digits and display them
      srand(time(&seed));
      for(int i=1;i<=digits;++i)
        printf("%d ",rand()%10);//output a random digit
  
      // wait one second 从这开始一直到检查输入之前，我知道有问题但我找不出是什么问题...
      for(;clock()-wait_start<delay*CLOCKS_PER_SEC;);
      
      //overwrite the digit sequence
      printf("\r");
      for(int i=1;i<=digits;i++)
      printf("  ");
      if(tries==1)
      printf("\nEnter the sequence\n");
      else
      printf("\r");
         
      //input sequence and check it against the original
      srand(seed);//reinitialize sequence
      for(int i=1;i<=digits;i++)
      {
        scanf("%d",&number);
        getchar();
        if(number!=rand()%10)
        {
          correct = false;
          break;
        }
      }

      //on every third successful try, increase length         
      if(correct &&((tries%3)==0))
        ++digits;
            
      printf("%s\n",correct?"Correct!":"Wrong!");
    }
   
      //output the score when game finished
      score=10*(digits-((tries%3)==1));
      total_digits=digits*(((tries%3)==0)?3:tries%3);
      if(digits>2)
      total_digits+=3*((digits-1)*(digits-2)/2-1);
      game_time=(clock()-start_time)/CLOCKS_PER_SEC-tries*delay;
      if(total_digits>game_time)
      score+=10*(game_time-total_digits);
      printf("\n\nGame time was %ds,"
             " Your score is %d\n",game_time,score);
      fflush(stdin);

      //check if user required new game
      printf("\nDo you want to play again?(y/n):");        
      scanf("%c",&play_again);//这个scanf会被跳过
  }
    while(tolower(play_again)=='y');
  
  return 0;
}