#include "stdio.h"#include "stdlib.h"#include "time.h" int main(void){ int number[20]; int i,j; srand((unsigned)time(NULL)); for(i=0;i<20;i++) { number[i]=1+rand()%20; for(j=0;j<i;j++) { if(number[i]==number[j]) i--; } } for(i=0;i<20;i++) { if(i%10==0) putchar('\n'); printf("%5d"...