Merge branch 'main' into file

Author: SjxSubham

152. Maximum-Product-Subarray.cpp

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+// 152. Maximum Product Subarray
+// By Traversing in Both Directions 
+// Time Complexity - O(n) and Space Complexity - O(1) 
+class Solution {
+public:
+    int maxProduct(vector<int>& nums) {
+        int n = nums.size();
+        int maxi = INT_MIN;
+        int ltr = 1, rtl = 1;
+        for(int i=0; i<n; i++){
+            if(ltr == 0){
+                ltr = 1;
+            }
+            if(rtl == 0){
+                rtl = 1;
+            }
+
+            ltr *= nums[i];
+            int j = n-i-1;
+            rtl *= nums[j];
+
+            maxi = max({ltr,rtl,maxi});
+        }
+        return maxi;
+    }
+};

2894. Divisible and Non-Divisible SumDifferences.cpp

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+class Solution {
+public:
+    int differenceOfSums(int n, int m) {
+        int ans=0;
+        for(int i=1;i<=n;i++){
+            if(i%m==0) ans-=i;
+            else ans+=i;
+
+        }
+        return ans;
+    }
+};

2894. Divisible and Non-divisible Sums Difference.cpp

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+class Solution {
+public:
+    int differenceOfSums(int n, int m) {
+        int num1 = 0, num2 = 0;
+        for (int i = 1; i <= n; i++) {
+            if (i % m == 0)
+                num2 += i;   // divisible by m
+            else
+                num1 += i;   // not divisible by m
+        }
+        return num1 - num2;
+    }
+};

3355. Zero Array Transformation I.cpp

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+#include <vector>
+using namespace std;
+
+class Solution {
+public:
+    bool isZeroArray(vector<int>& nums, vector<vector<int>>& queries) {
+        int n = nums.size();
+        vector<int> diff(n + 1, 0);
+
+        for(const auto& q : queries){
+            int l = q[0], r = q[1];
+            diff[l] += 1;
+            if(r + 1 < n){
+                diff[r + 1] -= 1;
+            }
+        }
+
+        int coverage = 0;
+        for(int i = 0; i < n; ++i){
+            coverage += diff[i];
+            if(nums[i] > coverage){
+                return false;
+            }
+        }
+        return true;
+    }
+};

355. Design Twitter.cpp

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+class Twitter {
+private:
+    int time;
+    unordered_map<int, unordered_set<int>> mp; // Stores followers
+    unordered_map<int, vector<pair<int, int>>> mp2; // Stores tweets (time, tweetId)
+public:
+    Twitter() {
+        time=0;
+    }
+    
+    void postTweet(int userId, int tweetId) {
+        mp2[userId].emplace_back(time,tweetId);
+        time++;
+    }
+    
+    vector<int> getNewsFeed(int userId) {
+        priority_queue<pair<int,int>> pq;
+        for(auto i: mp2[userId]) pq.push(i);
+        for(auto i: mp[userId]){
+            for(auto j: mp2[i]) pq.push(j);
+        }
+        vector<int> feed;
+        int count=10;
+        while(!pq.empty() && count){
+            feed.push_back(pq.top().second);
+            pq.pop();
+            count--;
+        }
+        return feed;
+    }
+    
+    void follow(int followerId, int followeeId) {
+        mp[followerId].insert(followeeId);
+    }
+    
+    void unfollow(int followerId, int followeeId) {
+    mp[followerId].erase(followeeId); 
+}
+};
+
+/**
+ * Your Twitter object will be instantiated and called as such:
+ * Twitter* obj = new Twitter();
+ * obj->postTweet(userId,tweetId);
+ * vector<int> param_2 = obj->getNewsFeed(userId);
+ * obj->follow(followerId,followeeId);
+ * obj->unfollow(followerId,followeeId);
+ */