public class Solution {
    public int removeDuplicates(int[] A) {
        int count = 0; 
        if (A == null || A.length == 0) {
            return count;
        }
        count = 1;
        // 從索引1開(kāi)始遍歷，獲得不重復(fù)個(gè)數(shù)
        for (int i = 1; i < A.length; i++) {
            if (A[i] != A[i - 1]) {
                count ++;
            }
        }
        
        int uniqueIndex = 1; // 記錄已經(jīng)有了多少個(gè)不重復(fù)的數(shù)字被換到了前面
        for (int i = 1; i < A.length; i++) {
            if (A[i] != A[i-1]) {
                A[uniqueIndex] = A[i];
                uniqueIndex++;
            }

        }
        return count;
    }
}