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Print all permutation of a string using ArrayList in Java
In this problem, we are given a string of size n and we have to print all permutations of the string. But this time we have to print this permutation using ArrayList.
Let’s take an example to understand the problem -
Input − string = ‘XYZ’
Output − XYZ, XZY, YXZ, YZX, ZXY, ZYX
To solve this problem, we will be generating all permutations of the character of the string. We will use a recursive function and will return arrayList.
Example
The following is ArrayList implementation of the algorithm −
import java.util.ArrayList;
public class Main{
static void printArrayList(ArrayList<String> combo) {
combo.remove("");
for (int i = 0; i < combo.size(); i++)
System.out.print(combo.get(i)+"\t");
}
public static ArrayList<String> generatePermutation(String str) {
if (str.length() == 0) {
ArrayList<String> empty = new ArrayList<>();
empty.add("");
return empty;
}
char ch = str.charAt(0);
String subStr = str.substring(1);
ArrayList<String> lastCombination = generatePermutation(subStr);
ArrayList<String> newCombination = new ArrayList<>();
for (String val : lastCombination) {
for (int i = 0; i <= val.length(); i++) {
newCombination.add(val.substring(0, i) + ch + val.substring(i));
}
}
return newCombination;
}
public static void main(String[] args) {
String str = "NOPQ";
System.out.println("Permutations of string are :");
printArrayList(generatePermutation(str));
}
}Output
Permutations of string are : NOPQ ONPQ OPNQ OPQN NPOQ PNOQ PONQ POQN NPQO PNQO PQNO PQON NOQP ONQP OQNP OQPN NQOP QNOP QONP QOPN NQPO QNPO QPNO QPON
Updated on: 14-Jul-2020
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