剑指 Offer 56 I. 数组中数字出现的次数

class Solution {
    public int[] singleNumbers(int[] nums) {
        Arrays.sort(nums);
        int i = 1,j = 0;
        int c = 0;
        ArrayList<Integer> list = new ArrayList<>();
        while(i<nums.length){
            if(nums[i] != nums[j]){
                c++;
                list.add(nums[j]);
                j = i;
                i++;
            }else{
                i+=2;
                j+=2;
                if(j == nums.length-1){
                    c++;
                    list.add(nums[j]);
                    break;
                }
            }
        }
        int[] res = new int[c];
        for(int k = 0;k<c;k++){
            res[k] = list.get(k);
        }
        return res;
    }
}

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位分组

public int[] singleNumbers(int[] nums) {
        int n = nums.length;
        int res = nums[0];
        int i = 1;
        while(i<n){
            res = (res^nums[i++]);
        }
        //将res转换为二进制数
        String s = Integer.toBinaryString(res);
        int j = s.length()-1;
        while (j>=0){
            if(s.charAt(j) == '1'){
                break;
            }else{
                j--;
            }
        }
        int j1 = s.length()-1-j;
        ArrayList<Integer> list1 = new ArrayList<>();
        ArrayList<Integer> list2 = new ArrayList<>();
        for (int num : nums) {
            String s1 = Integer.toBinaryString(num);
            if(s1.length() - 1 - j1<0){
                list2.add(num);
            }else {
                char c = s1.charAt(s1.length() - 1 - j1);
                if (c == '1') {
                    list1.add(num);
                } else {
                    list2.add(num);
                }
            }
        }
        int[] resList = new int[2];

        int res1 = list1.get(0);
        int k1 = 1;
        while(k1<list1.size()){
            res1 = (res1^list1.get(k1++));
        }
        int res2 = list2.get(0);
        int k2 = 1;
        while(k2<list2.size()){
            res2 = (res2^list2.get(k2++));
        }
        resList[0] = res1;
        resList[1] = res2;
        return resList;
    }

---

public int[] singleNumbers(int[] nums) {
        int n = nums.length;
        int res = 0;
        for(int num:nums){
            res ^= num;
        }
        //获取res中最低位的1
        int mask = 1;
        while ((res & mask) == 0){
            mask <<= 1;
        }
        int a = 0,b = 0;
        for(int num:nums){
            if((num & mask) == 0){
                a ^= num;
            }else{
                b^=num;
            }
        }
        return new int[]{a,b};
    }