Given an integer array of size n, find all elements that appear more than ⌊ n/3 ⌋ times.
Note
The algorithm should run in linear time and in O(1) space.
Example
No.1
Input: [3,2,3]
Output: [3]
No.2
Input: [1,1,1,3,3,2,2,2]
Output: [1,2]
Code
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public List<Integer> (int[] nums) {
List<Integer> result = new ArrayList<>();
int candidate1 = 0;
int candidate2 = 0;
int count1 = 0;
int count2 = 0;
for (int num : nums) {
if (num == candidate1)
count1++;
else if (num == candidate2)
count2++;
else if (count1 == 0) {
count1 = 1;
candidate1 = num;
}
else if (count2 == 0) {
count2 = 1;
candidate2 = num;
}
else {
count1--;
count2--;
}
}
count1 = 0;
count2 = 0;
for (int num : nums) {
if (num == candidate1)
count1++;
else if (num == candidate2)
count2++;
}
if (count1 > nums.length / 3)
result.add(candidate1);
if (count2 > nums.length / 3)
result.add(candidate2);
return result;
}
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