Given an int array which might contain duplicates, find if it is a sequence.

Given an int array which might contain duplicates, find if it is a sequence. 
Eg. {45,50,47,46,49,48}
is a sequence 45, 46,47,48,49,50
Sorting is an obvious solution. Can this be done in O(n) time and O(1) space

Approach:
Example array: A = {4, 1, 3, 3, 2}
1. get the min and max.
min=1 and max=4
2. if (max - min) > A.length then "its NOT a sequence".
3. else for each element in A[i] do the following:
a. calculate A[i] - min till A[i]-min=i;
i=0; 4 - 1 = 3, swap A[0] and A[3]
Now we have A = {3, 1, 3, 4, 2}
Again, 
i=0; 3 - 1 = 2, now A[0] and A[2] are same so swap A[0] and A[length-1] and put A[length] = infinite.
A = {2, 1, 3, 4, INF}
Again,
i=0; 2 - 1 = 1, swap A[0] and A[1], 
A = {1, 2, 3, 4, INF}
i=1; 2 - 1 = 1 (which is same as i)
similarlty for i=2, i=3
finally we have A as,
A = {1, 2, 3, 4, INF}

public class ArraySeq {
	public static void main(String[] args) {
		int[] A = { 45, 50, 47, 45, 50, 46, 49, 48, 49 };
		System.out.println("Printing Original Array ...");
		printArr(A);
		System.out.println("Is Sequence: " + isSequence(A));

	}

	public static boolean isSequence(int[] A) {
		int len = A.length;
		int MIN = Integer.MAX_VALUE;
		int MAX = Integer.MIN_VALUE;
		boolean result = false;
		for (int i = 0; i < len; i++) {
			if (A[i] < MIN) {
				MIN = A[i];
			}
			if (A[i] > MAX) {
				MAX = A[i];
			}
		}
		System.out.println("MIN:" + MIN + "  " + "MAX:" + MAX);
		if ((MAX - MIN) >= len) {
			return result;
		}
		int i = 0;
		while (i < len) {
			while ((i < len) && (i != (A[i] - MIN))) {
				if (A[A[i] - MIN] == A[i]) {
					A[i] = A[len - 1];
					A[len - 1] = Integer.MAX_VALUE;
					len = len - 1;
				} else {
					int k = A[i] - MIN;
					int temp = A[i];
					A[i] = A[k];
					A[k] = temp;
				}
			}
			++i;
		}
		System.out.println("Final Array ... ");
		printArr(A);
		for (i = 1; i < len; i++) {
			if ((A[i] - A[i - 1]) != 1) {
				return false;
			}
		}
		return true;
	}

	public static void printArr(int[] A) {
		int len = A.length;
		for (int i = 0; i < len; i++) {
			System.out.print(A[i] + " ");
		}
		System.out.println();
	}
}