LeetCode Weekly Contest 283

class Solution
{
public:

    vector<string> cellsInRange(string s)
    {
        vector<string> ans;
        
        for (char r = s[0]; r <= s[3]; r++)
        {
            for (char c = s[1]; c <= s[4]; c++)
            {
                string tmp = "";
                
                tmp.push_back(r);
                tmp.push_back(c);
                
                ans.push_back(tmp);
            }
        }
        
        return ans;
    }
};

typedef long long ll;

class Solution
{
public:

    long long minimalKSum(vector<int>& nums, int k)
    {
        sort(nums.begin(), nums.end());
        
        ll ans = 0;
        
        for (ll i = 0, prev = 0; i < nums.size(); i++)
        {   
            ll d = min(nums[i] - prev - 1, (ll) k);
            
            if (d > 0)
            {
                ans += ((prev + 1) + (prev + d)) * d / 2;
                k -= d;
            }
            
            prev = nums[i];
        }
        
        if (k > 0)
        {
            ans += (((ll) nums.back() + 1) + ((ll) nums.back() + k)) * k / 2;
        }
        
        return ans;
    }
};

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution
{
public:
    
    unordered_map<int, TreeNode*> nodes;
    
    TreeNode *getNode(int x)
    {
        if (nodes.find(x) == nodes.end())
        {
            nodes[x] = new TreeNode(x, NULL, NULL);
        }
        
        return nodes[x];
    }
    
    TreeNode* createBinaryTree(vector<vector<int>>& descriptions)
    {
        unordered_set<int> all, children;
        
        for (auto &desc : descriptions)
        {
            int parent = desc[0], child = desc[1], isLeft = desc[2];
            
            if (isLeft == 1)
            {
                getNode(parent)->left = getNode(child);
            }
            else
            {
                getNode(parent)->right = getNode(child);
            }
            
            all.insert(parent);
            all.insert(child);
            children.insert(child);
        }
        
        for (auto &x : all)
        {
            if (children.find(x) == children.end())
            {
                return getNode(x);
            }
        }
        
        return NULL;
    }
};

typedef long long ll;

class Solution
{
public:
    
    vector<int> replaceNonCoprimes(vector<int>& nums)
    {
        vector<int> ans;
        
        for (auto &num : nums)
        {
            ans.push_back(num);
            
            while (ans.size() >= 2)
            {
                int x = ans[ans.size() - 2], y = ans[ans.size() - 1];
                int d = __gcd(x, y);
                
                if (d == 1)
                {
                    break;
                }
                
                ans[ans.size() - 2] = ((ll) x * y) / d;
                ans.pop_back();
            }
        }
        
        return ans;
    }
};