PTA 7-1 string sorting (10 points)

This question requires the preparation of procedures , Read in 5 A string , Output in order of small to large .
Input format ：
Input is space delimited 5 Non empty strings , Each string does not contain spaces 、 tabs 、 Blank characters such as line breaks , The length is less than 80.
Output format ：
Output the sorted results in the following format ：
After sorted:
One string per line
sample input ：
red yellow blue black white
No blank lines at the end

• #include<string.h>
  int main()
  {
  int i,j;
  char s[5][80],t[80];
  for(i=0;i<5;i++) // What's this for ？

    scanf("%s",s[i]);     // Why not s[i][j]？

  for(i=0;i<4;i++) // Why is there less than four ？

    for(j=0;j<4-i;j++)    //j＜4-i  What do you mean ？

  if(strcmp(s[j],s[j+1])>0) this strcmp（） I can't understand why it's written like this ？
  {

   strcpy(t,s[j]);  strcpy(s[j],s[j+1]);  strcpy(s[j+1],t);

  }
  printf("After sorted:\n");
  for(i=0;i<5;i++) // Why do you want one here for loop , Why? i Less than 5 了 ？

    printf("%s\n",s[i]);

  return 0;
  }

Can someone give me a detailed analysis ？ I can't understand the program , In addition to the questions I raised above , The boss can have other explanations . Please, please, please , Teach me .