Initial commit

Author: PhoenixDD

1150-Check If a Number Is Majority Element in a Sorted Array.cpp

@@ -0,0 +1,29 @@
+//log(n)
+class Solution {
+public:
+    bool isMajorityElement(vector<int>& nums, int target) 
+    {
+        if(nums[nums.size()/2]!=target)
+            return false;
+        int j=nums.size()-1,i=0,mid,start;
+        while(i<j)                          //simulate lower_bound
+        {
+            mid=(i+j)>>1;
+            if(nums[mid]>=target)
+                j=mid;
+            else
+                i=mid+1;
+        }
+        start=i;
+        i=start,j=nums.size()-1;
+        while(i<j)                          //Simulate upper_bound
+        {
+            mid=(i+j)>>1;
+            if(nums[mid]<=target)
+                i=mid+1;
+            else
+                j=mid;
+        }
+        return (i==nums.size()-1?1:0)+i-start>nums.size()/2;
+    }
+};

1151-Minimum Swaps to Group All 1's Together.cpp

@@ -0,0 +1,17 @@
+class Solution {
+public:
+    int minSwaps(vector<int>& data) 
+    {
+        int total1s=0,start=0,count=0,result=INT_MAX;
+        for(int &i:data)
+            total1s+=i;
+        for(int i=0;i<data.size();i++)
+        {
+            count+=data[i]==1;
+            if(i-start+1>total1s)
+                count-=data[start++]==1;
+            result=min(result,total1s-count);
+        }
+        return result;
+    }
+};

1153-String Transforms Into Another String.cpp

@@ -0,0 +1,19 @@
+/*Cases to consider "ab"->"ba" and "abc...z"-> "z,y,x....a"
+Key is that we always need a temporary character to transform other characters
+to their mapping which is not in the string */
+class Solution {
+public:
+    bool canConvert(string str1, string str2) 
+	{
+        if(str1==str2)				//Corner case
+			return true;
+		vector<char> map(26,'-');
+		for(int i=0;i<str1.size();i++)
+		{
+			if(map[str1[i]-'a']!='-'&&map[str1[i]-'a']!=str2[i])//Already mapped but different character is always false
+				return false;
+			map[str1[i]-'a']=str2[i];
+		}
+		return unordered_set(str2.begin(),str2.end())<26;//Check if there is atleast 1 character that is not included and this can be used as temp to swap	
+    }
+};

1165-Single-Row Keyboard.cpp

@@ -0,0 +1,13 @@
+class Solution {
+public:
+    int calculateTime(string keyboard, string word) 
+    {
+        vector<int> keyIndices(26,-1);
+        for(int i=0;i<keyboard.length();i++)
+            keyIndices[keyboard[i]-'a']=i;
+        int start=0,result=0;
+        for(char &c:word)
+            result+=abs(start-keyIndices[c-'a']),start=keyIndices[c-'a'];
+        return result;
+    }
+};

1166-Design File System.cpp

@@ -0,0 +1,36 @@
+class FileSystem {
+public:
+    FileSystem() 
+    {
+        paths[""]=-1;
+    }
+    
+    bool create(string path, int value) 
+    {
+        if(paths.count(path.substr(0,path.find_last_of('/'))))
+        {
+            paths[path]=value;
+            return true;
+        }
+        return false;
+    }
+    
+    int get(string path) 
+    {
+        it=paths.find(path);
+        if(it!=paths.end())
+            return it->second;
+        return -1;
+    }
+    private:
+    unordered_map<string,int> paths;
+    unordered_map<string,int>::iterator it;
+    string temp;
+};
+
+/**
+ * Your FileSystem object will be instantiated and called as such:
+ * FileSystem* obj = new FileSystem();
+ * bool param_1 = obj->create(path,value);
+ * int param_2 = obj->get(path);
+ */

1167-Minimum Cost to Connect Sticks.cpp

@@ -0,0 +1,16 @@
+class Solution {
+public:
+    int connectSticks(vector<int>& sticks) 
+    {
+        int result=0,first,second;
+        priority_queue<int,vector<int>,greater<int>> pq(sticks.begin(),sticks.end());
+        while(pq.size()>1)
+        {
+            first=pq.top(),pq.pop();
+            second=pq.top(),pq.pop();
+            result+=first+second;
+            pq.push(first+second);
+        }
+        return result;
+    }
+};

1168-Optimize Water Distribution in a Village.cpp

@@ -0,0 +1,36 @@
+//Kruskal's MST, treat house 0(imaginary) which is the first well, and pipes 0 to each house is the well dig cost
+class Solution {
+public:
+    vector<int> parent,Rank;
+    int Find(int x)
+    {
+        return parent[x]==x?x:parent[x]=Find(parent[x]);
+    }
+    void Union(int x,int y)
+    {
+        int xset=Find(x),yset=Find(y);
+        if(xset!=yset)
+        {
+            Rank[xset]<Rank[yset]?parent[xset]=yset:parent[yset]=xset;
+            if(Rank[xset]==Rank[yset])
+                Rank[xset]++;
+        }
+    }
+    int minCostToSupplyWater(int n, vector<int>& wells, vector<vector<int>>& pipes) 
+    {
+        Rank.resize(n+1,0),parent.resize(n+1);
+        for(int i=0;i<parent.size();i++)
+            parent[i]=i;
+        for(int i=0;i<wells.size();i++)
+            pipes.push_back({0,i+1,wells[i]});
+        sort(pipes.begin(),pipes.end(),[](vector<int>&l,vector<int>&r){return l[2]<r[2];});
+        int result=0;
+        for(vector<int>&v:pipes)
+            if(Find(v[0])!=Find(v[1]))
+            {
+                result+=v[2];
+                Union(v[0],v[1]);
+            }
+        return result;
+    }
+};

295-Find Median from Data Stream_2.cpp

@@ -0,0 +1,35 @@
+class MedianFinder {
+public:
+    /** initialize your data structure here. */
+    MedianFinder() {
+    }
+    
+    void addNum(int num) 
+    {
+        sorted.insert(num);
+        if(sorted.size()==1)
+            mid_1=sorted.begin();
+        else if(num<*mid_1)
+        {
+            if(sorted.size()%2==0)
+                mid_1--;
+        }
+        else if(sorted.size()&1)
+            mid_1++;
+    }
+    
+    double findMedian() 
+    {
+        return sorted.size()&1?*mid_1:((double)*(++(mid_2=mid_1))+*mid_1)/2;
+    }
+    private:
+    multiset<int> sorted;
+    multiset<int>::iterator mid_1,mid_2;
+};
+
+/**
+ * Your MedianFinder object will be instantiated and called as such:
+ * MedianFinder* obj = new MedianFinder();
+ * obj->addNum(num);
+ * double param_2 = obj->findMedian();
+ */

295-Find Median from Data Stream_3.cpp

@@ -0,0 +1,25 @@
+class MedianFinder {
+public:
+    /** initialize your data structure here. */
+    priority_queue<int> left;
+    priority_queue<int,vector<int>,greater<int>> right;
+    void addNum(int num) 
+    {
+        left.push(num);
+        right.push(left.top());                             //Balance eg, 1,2,3 (put to 3 right and get 2 put it to left)
+        left.pop();
+        if(left.size()<right.size())
+            left.push(right.top()),right.pop();
+    }
+    double findMedian() 
+    {
+        return (left.size()+right.size())&1?left.top():((double)left.top()+right.top())/2;
+    }
+};
+
+/**
+ * Your MedianFinder object will be instantiated and called as such:
+ * MedianFinder obj = new MedianFinder();
+ * obj.addNum(num);
+ * double param_2 = obj.findMedian();
+ */