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Premute.java
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113 lines (83 loc) · 3.3 KB
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package Algorithms.algorithm.others;
import java.util.ArrayList;
import java.util.Arrays;
public class Premute {
public static void main(String[] args){
int[] number = {2,1,1,3};
//ArrayList<ArrayList<Integer>> result = permute(number);
ArrayList<ArrayList<Integer>> result = permuteUnique(number);
System.out.println(result.toString());
}
public static ArrayList<ArrayList<Integer>> permute(int[] num) {
ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
ArrayList<Integer> list = new ArrayList<Integer>();
premuteHelp(result, list, num, 0);
return result;
}
public static ArrayList<ArrayList<Integer>> premuteHelp(ArrayList<ArrayList<Integer>> result,
ArrayList<Integer> list, int[] input, int pos){
result.add(new ArrayList<Integer>(list));
for (int i = pos; i < input.length; i ++){
list.add(input[i]);
premuteHelp(result, list, input, i+1);
list.remove(list.size()-1);
}
//if (list.size() == input.length){
//}
return result;
}
public static ArrayList<ArrayList<Integer>> permuteUnique(int[] num) {
ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
ArrayList<Integer> list = new ArrayList<Integer>();
// record the numbers which has been accessed.
boolean[] numFlag = new boolean[num.length];
for(int i = 0; i < numFlag.length; i++) {
numFlag[i] = false;
}
// sort the array.
Arrays.sort(num);
permuteUniqueHelp(result, list, num, numFlag);
return result;
}
public static void permuteUniqueHelp(ArrayList<ArrayList<Integer>> result,
ArrayList<Integer> list, int[] num, boolean[] numFlag) {
if (list.size() == num.length) {
result.add(new ArrayList<Integer>(list));
return;
}
/*
for (int i = 0; i < num.length; i ++){
while (i < num.length - 1 && num[i] == num[i + 1] ) {
// skip the duplicate characters.
i++;
}
if (numFlag[i] == false) {
list.add(num[i]);
numFlag[i] = true;
}else{
continue;
}
permuteUniqueHelp(result, list, num, numFlag);
list.remove(list.size() - 1);
numFlag[i] = false;
}
*/
for (int i = 0; i < num.length; i ++){
// if numFlag[i-1] has been accessed, we should open the access of all the duplicates
if (i > 0 && num[i] == num[i - 1] && numFlag[i-1] == false) {
// skip the duplicate characters.
continue;
}
if (numFlag[i] == false) {
list.add(num[i]);
numFlag[i] = true;
}else{
continue;
}
permuteUniqueHelp(result, list, num, numFlag);
list.remove(list.size() - 1);
numFlag[i] = false;
}
return;
}
}