June 13 ques

Author: Rishabh0210

JuneLeetCodingChallenge2020/Insert_Delete_GetRandomO(1).cpp

@@ -0,0 +1,50 @@
+//https://leetcode.com/explore/challenge/card/june-leetcoding-challenge/540/week-2-june-8th-june-14th/3358/
+
+class RandomizedSet {
+public:
+    /** Initialize your data structure here. */
+    vector<int> v;
+    map<int, int> index_map;
+    int size;
+    RandomizedSet() {
+        size = 0;
+    }
+    
+    /** Inserts a value to the set. Returns true if the set did not already contain the specified element. */
+    bool insert(int val) {
+        if(index_map.find(val) != index_map.end())
+            return false;
+        v.push_back(val);
+        index_map[val] = size;
+        size++;
+        return true;
+    }
+    
+    /** Removes a value from the set. Returns true if the set contained the specified element. */
+    bool remove(int val) {
+        if(index_map.find(val) == index_map.end())
+            return false;
+        int i = index_map[val];
+        v[i] = v[size - 1];
+        index_map[v[size - 1]] = i;
+        
+        v.pop_back();
+        index_map.erase(val);
+        size--;
+        return true;
+    }
+    
+    /** Get a random element from the set. */
+    int getRandom() {
+        int i = rand() % size;
+        return v[i];
+    }
+};
+
+/**
+ * Your RandomizedSet object will be instantiated and called as such:
+ * RandomizedSet* obj = new RandomizedSet();
+ * bool param_1 = obj->insert(val);
+ * bool param_2 = obj->remove(val);
+ * int param_3 = obj->getRandom();
+ */

JuneLeetCodingChallenge2020/Sort_Colours.cpp

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+//https://leetcode.com/explore/challenge/card/june-leetcoding-challenge/540/week-2-june-8th-june-14th/3357/
+
+
+class Solution {
+private:
+    void swap(vector<int>& nums, int a, int b) {
+        int temp = nums[a];
+        nums[a] = nums[b];
+        nums[b] = temp;
+    }
+public:
+    void sortColors(vector<int>& nums) {
+        int l, m, h, i;
+        l = m = 0;
+        h = nums.size() - 1;
+        
+        while(m <= h) {
+            if(nums[m] == 0) {
+               swap(nums, l++, m++); 
+            } else if (nums[m] == 1) {
+                m++;
+            } else if (nums[m] == 2) {
+                swap(nums, m, h--);
+            }
+        }
+    }
+};