xzhang311

class Solution {
public:
    int rangeBitwiseAnd(int m, int n) {
        int res = m&n;
        int diff = log2(n-m);
        int tmp = 1;
        for(int i=0; i<=diff; i++)
            res = res&((~tmp)<<i);
        return res;
    }

xzhang311

class Solution {
public:
    int minSubArrayLen(int s, vector<int>& nums) {
        int res=INT_MAX;
        if(nums.empty())
            return 0;

        int p0=0, p1=0;
        int sum = 0;
        for(; p1<=nums.size(); ){

xzhang311

class Solution {
public:
    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
        TreeNode* res=NULL;
        if(root==NULL)
            return res;
        
        if(p->val>q->val)
            return lowestCommonAncestor(root, q, p);
        

xzhang311

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {

xzhang311

class Solution {
public:

    void buildGraph(vector<string>& words, vector<int>& charsAll, vector<set<char> >& pntTo, vector<set<char> >& pntBy){
        for(int i=0; i<words.size(); i++){
            string word1=words[i];
            for(int j=0; j<word1.length(); j++)
                charsAll[word1[j]-'a']=1;
        }
        for(int i=0; i<words.size()-1; i++){

xzhang311

class Solution {
public:
    int missingNumber(vector<int>& nums) {
        int result = nums.size();
        int i=0;
        
        for(int num:nums){
            result ^= num;
            result ^= i;
            i++;

xzhang311

class Solution {
public:
    
    void BuildGraph(const vector<string>& words,  unordered_map<char, unordered_set<int> >& pointTo,  unordered_map<char, unordered_set<int> >& pointBy){
        for(int i=0; i<words.size()-1; i++){
            string w0 = words[i];
            string w1 = words[i+1];

            for(int j=0; j<min(w0.length(), w1.length()); j++){
                if(w0[j]!=w1[j]){

xzhang311

// Forward declaration of isBadVersion API.
bool isBadVersion(int version);

class Solution {
public:
    int firstBadVersion(int n) {
        int l = 1, r=n;
        while(l<r-1){
            int m = l+(r-l)/2;
            bool tmp = isBadVersion(m);

xzhang311

class Solution {
public:
    int numSquares(int n) {
        vector<int> myT(n+1, INT_MAX);
        myT[0]=0;
        
        for(int i=1; i<=n; i++){
            for(int j=1; j*j<=i; j++)
                myT[i] = min(myT[i], myT[i-j*j]+1); 
        }

xzhang311

void wiggleSort(vector<int>& nums) {
    if (nums.empty()) {
        return;
    }
    int n = nums.size();

    // Step 1: Find the median
    vector<int>::iterator nth = next(nums.begin(), n / 2);
    nth_element(nums.begin(), nth, nums.end());
    int median = *nth;