杂乱的code

 

/*o(n)的堆化方法*/

void myjust(vector<int>& A,int i)
{
int l=i*2+1;
int r=i*2+2;
int minn=i;
if(l<A.size()&&A[l]<A[minn])
minn=l;
if(r<A.size()&&A[r]<A[minn])
minn=r;
if(minn!=i)
{
swap(A[minn],A[i]);
myjust(A,minn);
}
}

void heapify(vector<int> &A) {
int lens=A.size();
if(lens==0) return;
for(int i=lens/2;i>=0;i--)
{
myjust(A,i);
}
}

 

求sqrt(double x)

 

 

 

键树

class Trie {
public:

	struct TrieNode {
		bool isEnd;
		map<char, TrieNode*> myMap;
		TrieNode()
		{
			isEnd = false;
		}
	};

	TrieNode* root;
	/** Initialize your data structure here. */
	Trie() {
		root = new TrieNode();
	}

	/** Inserts a word into the trie. */
	void insert(string word) {
		TrieNode* current = root;
		for (int i = 0; i < word.length(); i++)
		{
			if (current->myMap.find(word[i]) != current->myMap.end())
			{
				current = current->myMap[word[i]];
				if (i == word.length() - 1)
					current->isEnd = true;
			}
			else
			{
				TrieNode* tmp = new TrieNode();
				tmp->isEnd = (i == word.length() - 1 ? true : false);
				current->myMap[word[i]] = tmp;
				current = tmp;
			}
		}
	}

	/** Returns if the word is in the trie. */
	bool search(string word) {
		TrieNode* current = root;
		for (int i = 0; i < word.length(); i++)
		{
			if (current->myMap.find(word[i]) != current->myMap.end())
			{
				current = current->myMap[word[i]];
			}
			else
			{
				return false;
			}
		}
		return current->isEnd == true ? true : false;
	}

	/** Returns if there is any word in the trie that starts with the given prefix. */
	bool startsWith(string prefix) {
		TrieNode* current = root;
		for (int i = 0; i < prefix.length(); i++)
		{
			if (current->myMap.find(prefix[i]) != current->myMap.end())
			{
				current = current->myMap[prefix[i]];
			}
			else
			{
				return false;
			}
		}
		return true;
	}
};

 

//寻找前k大小的数

int getIdx(vector<int>& nums,int left,int right)
{
    int tmp=nums[left];
    while(left<right)
    {
        while (left<right&&nums[right]>=tmp)
            right--;
        nums[left]=nums[right];
        while (left<right&&nums[left]<tmp)
            left++;
        nums[right]=nums[left];
    }
    nums[left]=tmp;
    return left;
}

vector<int> GetLeastNumbers_Solution(vector<int> input, int k) {

    vector<int> ans;
    if(input.size()<k||k<=0||input.size()==0)
    {
        return ans;
    }
    int idx=-1;
    int left=0,right=input.size()-1;
    while (idx!=k-1)
    {
        idx=getIdx(input,left,right);
        if(idx>k-1)
        {
            right=idx-1;
        }
        else
        {
            left=idx+1;
        }
    }
    for(int i=0;i<k;i++)
    {
        ans.push_back(input[i]);
    }
    return ans;
}