int i,j,vec[15]={0};
srand (time(NULL));
for (i=0;i<15;i++){
vec[i]=rand() % 25+1;
for (j=0;j<15;j++){
if (i!=j){
while(vec[i]==vec[j]){
vec[i]=rand() % 25+1;
}
}
}
printf("%d\n",vec[i]);
}
return 0;
}
the code still gives me repeated numbers
EXAMPLE: 24 3 7 20 18 10 12 17 9 7 4 25 13 15 21
I cant figure out what to do with it
Reset j in the while loop:
for (j=0;j<i;j++){ //Use j<i
if (i!=j){
while(vec[i]==vec[j]){
vec[i]=rand() % 25+1;
j=-1;//-1 because in the next iteration,j will start from 0
}
}
}
You can use an array
int randNumbers[25]; // fill it starting 0 to 25 then randomize the number in a range between 0 and 25 after swap the number in the randomized index with the last number in your array
randomize 0 to 23 and so on....
int main(int argc, char **argv) {
static const int size = 25;
int numbers[size];
for( int i = 0; i < size; i++ ){
numbers[i] = i;
}
srand (time(NULL));
for( int i = 0; i < size; i++ ){
int rIndex = rand()%(size - i);
int rNum = numbers[rIndex];
numbers[rIndex] = numbers[size-i];
printf("%d ", rNum);
}
return 0;
}
O(n) complexity...
You have your loops mixed up. The logic is: Generate a random number until you have found one that isn't in the list.
The way you do it, you generate a new number inside the checking loop. But that doesn't work. Say you're generating the 4th number and find it is equal to the third. Then you generate a new one which might well be equal to any you have already checked against.
You also check uninitialised elements when j > i. Your inner loop should only run up to i.
So:
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
int main()
{
int vec[15] = { 0 };
int i, j;
srand(time(NULL));
for (i = 0; i < 15; i++) {
int okay = 0;
while (!okay) {
vec[i] = rand() % 25 + 1;
okay = 1;
for (j = 0; j < i; j++) {
if (vec[i] == vec[j]) okay = 0;
}
}
printf("%d\n", vec[i]);
}
return 0;
}
That still looks a bit awkward with that okay variable. In my opinion, checking for duplicates should be a separate function:
int contains(int arr[], int n, int x)
{
while (n--) {
if (arr[n] == x) return 1;
}
return 0;
}
int main()
{
// snip ...
for (i = 0; i < 15; i++) {
do {
vec[i] = rand() % 25 + 1;
} while (contains(vec, i, vec[i]));
printf("%d\n", vec[i]);
}
// snip ...
}
In your case the range of possible numbers isn't mich bigger than the number of array elements. You could also create an ordered array {1, 2, 3, ..., 25}, then shuffle it and use only the first 15 elements.
Are you actually trying to shuffle the numbers, rather than fill the array with randoms? (It looks like you want an array with numbers from 1 to 25, but in random order.) rand() can give you duplicate numbers (they're random, after all!)
Try this:
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <time.h>
int
main( int argc, char **argv )
{
int i, vec[25];
for (i = 0; i < 25; ++i) vec[i] = i + 1;
/* Shuffle entries */
srand( time( 0 ) );
for (i = 0; i < 1000; ++i) {
int a = rand( ) % 25;
int b = rand( ) % 25;
if (a != b) {
int tmp = vec[a];
vec[a] = vec[b];
vec[b] = tmp;
}
}
/* Print shuffled array */
for (i = 0; i < 25; ++i) printf( "%d: %d\n", i, vec[i] );
return 0;
}
#include<stdio.h>
#include<stdlib.h>
int inArray(int, int, int*);
int main()
{
int i,j,vec[15]={0};
int temp;
srand (time(NULL));
for (i=0;i<15;i++){
temp =rand() % 25+1;
while(inArray(i+1,temp, vec) == 1){
temp = rand() % 25+1;
}
vec[i] = temp;
printf("VECT[%d] \t= %d\n",i,vec[i]);
}
return 0;
}
int inArray(int count, int input, int* array){
int i = 0;
for(i=0; i<count; i++){
if(input == array[i]){
return 1;
}
}
return 0;
}
Gave an output:
VECT[0] = 24
VECT[1] = 19
VECT[2] = 1
VECT[3] = 25
VECT[4] = 22
VECT[5] = 18
VECT[6] = 7
VECT[7] = 8
VECT[8] = 12
VECT[9] = 21
VECT[10] = 11
VECT[11] = 6
VECT[12] = 23
VECT[13] = 20
VECT[14] = 15
The checking was off, you would change and not break allowing it to be changed to a previous value.
