top-k-frequent-elements

class minHeap {
// min Heap
private:
vector<pair<int, int> > array;
int alen;

void adjust_all() {
for (int k=alen-1; k>=0; --k) {
adjust(k);
}
}

void swap(int i, int j) {
int tmp = array[i].first;
array[i].first = array[j].first;
array[j].first = tmp;

tmp = array[i].second;
array[i].second = array[j].second;
array[j].second = tmp;
}

void adjust(int k) {
if (k*2+1 >= alen) {
return;
}
int j = k * 2 + 1;
if (k*2+2 < alen && array[k*2+1].second > array[k*2+2].second) {
j = k * 2 + 2;
}
if (array[k].second > array[j].second) {
swap(k, j);
adjust(j);
}
}

public:
minHeap(int n) {
alen = n;
}

void add(int num, int freq) {
if (array.size() < alen) {
array.push_back(make_pair(num, freq));
if (array.size() == alen) {
adjust_all();
}
}
else {
if (freq > array[0].second) {
array[0].first = num;
array[0].second = freq;
adjust(0);
}
}
}

vector<int> getArray() {
vector<int> ret;
for (int k=alen-1; k>=0; --k) {
ret.push_back(array[k].first);
}
return ret;
}

};

class Solution {
unordered_map<int, int> umap;
public:
vector<int> topKFrequent(vector<int>& nums, int k) {
int vlen = nums.size();
for (int i=0; i<vlen; ++i) {
if (umap.find(nums[i]) != umap.end()) {
umap[nums[i]] = umap[nums[i]] + 1;
}
else {
umap[nums[i]] = 1;
}
}

minHeap mh(k);
for (unordered_map<int, int>::iterator itr = umap.begin();
itr != umap.end(); ++itr) {

mh.add(itr->first, itr->second);
}
return mh.getArray();
}
};