有重复元素的全排列问题

package algorithms;

/**
* Created by sprint on 16-10-19.
*/
public class FullArray {

/**
*  思路：此程序是在全排列的基础上修改的。
*      1.掌握全排列后
*      2.添加条件：如果在arrays[i]前面含有　arrays[j] == arrays[i] 则不进行排列，否则进行排列。
*/

public static void permutation(int[] arrays, int left, int right) {
if (left == right) {
for (int key : arrays) {
System.out.print(key);
}
System.out.println();
} else {
for (int i = left; i <= right; i++) {
if (!isExit(arrays, left, i)) {
swap(arrays, left, i);
permutation(arrays, left+1, right);
swap(arrays, left, i);
}
}
}
}

public static void swap(int[] arrays, int leftValue, int rightValue) {
int tempValue = arrays[leftValue];
arrays[leftValue] = arrays[rightValue];
arrays[rightValue] = tempValue;
}

public static boolean isExit(int[] arrays, int left, int index) {
int key = arrays[index];
for (int i = left; i < index; i++) {
if (key == arrays[i]) {
return true;
}
}
return false;
}

public static void main(String[] args) {
int[] arrays = {1, 1, 2, 2};
permutation(arrays, 0, arrays.length-1);
}
}