icameling

class Solution {
public:
    string reverseWords(string s) {
        reverse(s.begin(), s.end());
        int str_len = 0;
        int l = -1;
        for (int i = 0; i < s.size(); ++i) {
            if (l >= 0 && s[i] == ' ') {
                reverse(s.begin() + l,  s.begin() + i);
                for (int k = 0; k < i - l; ++k) {

icameling

class Solution {
public:
    string replaceSpace(string s) {
        int space_cnt = count(s.begin(), s.end(), ' ');
        if (space_cnt < 0) return s;

        int lft = s.size() - 1;
        int rht = s.size() + space_cnt * 2 - 1;
        s.resize(s.size() + space_cnt * 2);
        for (; lft >= 0; lft--) {

icameling

class Solution {
public:
    string reverseStr(string s, int k) {
        int n = 0;
        for (int i = 0; i < s.size(); i += (2*k)) {
            if (i + k <= s.size())
                reverse(s.begin() + i, s.begin() + i + k);
            else 
                reverse(s.begin() + i, s.end());  
        }

icameling

class Solution {
public:
    void reverseString(vector<char>& s) {
        int left = 0, right = s.size() - 1;
        while (left < right) {
            char tmp = s[left];
            s[left] = s[right];
            s[right] = tmp;
            left++;
            right--;

icameling

class Solution {
public:

	inline void forward(vector<int>& nums, int k, int& j) {
        while (j < k && nums[j] == nums[j+1]) {
            j++;
        }
    }

    inline void backward(vector<int>& nums, int j, int& k) {

icameling

class Solution {
public:

    inline void forward(vector<int>& nums, int k, int& j) {
        while (j < k && nums[j] == nums[j+1]) {
            j++;
        }
    }

    inline void backward(vector<int>& nums, int j, int& k) {

icameling

class Solution {
public:
    bool canConstruct(string ransomNote, string magazine) {
	    if (ransomNote.size() > magazine.size()) return false;

        int table[26] = {0};
        for (int i = 0; i < magazine.size(); ++i) {
            table[magazine[i] - 'a']++;
        }
        for (int i = 0; i < ransomNote.size(); ++i) {

icameling

class Solution {
public:
    int fourSumCount(vector<int>& nums1, vector<int>& nums2, vector<int>& nums3, vector<int>& nums4) {
        int ret = 0;
        unordered_map<int, int> ab_map;
        for (int a : nums1) {
            for (int b : nums2) {
                ab_map[a+b]++;
            }
        }

icameling

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        unordered_map<int, int> nums_map;
        for (int i = 0; i < nums.size(); ++i){
            int k = target - nums[i];
            auto iter = nums_map.find(k);
            if (iter != nums_map.end()) {
                return {i, nums_map[k]}; 
            }

icameling

class Solution {
public:
    bool isHappy(int n) {
        unordered_set<int> nums;
        
        int sum = 0;
        while (sum != 1) {
            sum = 0;
            while (n > 0) {
                int k = n % 10;