lintcode-medium-Majority Number III

Given an array of integers and a number k, the majority number is the number that occurs

more than 1/k

of the size of the array.

Find it.

Notice

There is only one majority number in the array.

Example

Given

[3,1,2,3,2,3,3,4,4,4]

and

k=3

, return

3

.

Challenge

O(n) time and O(k) extra space

public class Solution {
/**
* @param nums: A list of integers
* @param k: As described
* @return: The majority number
*/
public int majorityNumber(ArrayList<Integer> nums, int k) {
// write your code

if(nums == null || nums.size() == 0 || k < 1)
return 0;

if(k == 1)
return nums.get(0);

HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();

int size = nums.size();

for(int i = 0; i < size; i++){
int temp = nums.get(i);

if(map.containsKey(temp)){
map.put(temp, map.get(temp) + 1);
}
else{
if(map.size() < k){
map.put(temp, 1);
}
else{
Iterator<Map.Entry<Integer, Integer>> it = map.entrySet().iterator();

while(it.hasNext()){
Map.Entry<Integer, Integer> entry = it.next();

if(entry.getValue() == 1){
it.remove();
}
else{
entry.setValue(entry.getValue() - 1);
}
}
}
}

}

int count = 0;
int result = 0;

for(Map.Entry<Integer, Integer> entry: map.entrySet()){
int candidate = entry.getKey();
int num = 0;
for(int i = 0; i < size; i++)
if(nums.get(i) == candidate)
num++;

if(num > count){
count = num;
result = candidate;
}
}

return result;
}
}