I have a string array
"Ben", "Jim", "Ken"
how can I print the above array 3 times to look like this:
"Ben", "Jim", "Ken"
"Jim", "Ben", "Ken"
"Ken", "Jim", "Ben"
I just want each item in the initial array to appear as the first element. The order the other items appear does not matter.
more examples
Input
"a","b","c","d"
output
"a","b","c","d"
"b","a","c","d"
"c","b","a","d"
"d","a","c","d"
Method signature
public void printArray(String[] s){
}
Rather than give you straight-up code, I'm going to try and explain the theory/mathematics for this problem.
The two easiest ways I can come up with to solve this problem is to either
The first method would require you to iterate through the indices and then iterate through all the elements in the array and loop back to the beginning when necessary, terminating when you return to the original element.
The second method would require you to iterate through the indices, print original element, then proceed to iterate through the array from the beginning, skipping the original element.
As you can see, both these methods require two loops (as you are iterating through the array twice)
In pseudo code, the first method could be written as:
for (i = array_start; i < array_end; i++) {
print array_element[i]
for (j = i + 1; j != i; j++) {
if (j is_larger_than array_end) {
set j equal to array_start
}
print array_element[j]
}
}
In pseudo code, the second method could be written as:
for (i = array_start; i < array_end; i++) {
print array_element[i]
for (j = array_start; j < array_end; j++) {
if (j is_not_equal_to i) {
print array_element[j]
}
}
}
public void printArray(String[] s){
for (int i = 0; i < s.length; i++) {
System.out.print("\"" + s[i] + "\",");
for (int j = 0; j < s.length; j++) {
if (j != i) {
System.out.print("\"" + s[j] + "\",");
}
}
System.out.println();
}
}
This sounds like a homework question so while I feel I shouldn't answer it, I'll give a simple hint. You are looking for an algorithm which will give all permutations (combinations) of the "for loop index" of the elements not the elements themselves. so if you have three elements a,b,c them the index is 0,1,2 and all we need is a way to generate permutations of 0,1,2 so this leads to a common math problem with a very simple math formula.
for(int i=0;i<s.length;i++){
for(int j=i;j<s.length+i;j++) {
System.out.print(s[j%(s.length)]);
}
System.out.println();
}
Using mod is approppiate for this question. The indexes of the printed values for your first example are like this;
0 1 2
1 2 0
2 0 1
so if you write them like the following and take mod of length of the array (3 in this case) you will reach solution.
0 1 2
1 2 3
2 3 4
