Add already solved heap and map problems

Author: biqar

Heaps And Maps/Distinct Numbers in Window/README.md

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+### Distinct Numbers in Window
+
+Asked in: [Amazon](#)
+
+You are given an array of N integers, A<sub>1</sub>, A<sub>2</sub> ,…, A<sub>N</sub> and an integer K. Return the of count of distinct numbers in all windows of size K.
+
+Formally, return an array of size N-K+1 where i’th element in this array contains number of distinct elements in sequence A<sub>i</sub>, A<sub>i+1</sub> ,…, A<sub>i+k-1</sub>.
+
+Note:
+```
+ If K > N, return empty array.
+ A[i] is a signed integer
+```
+For example,
+```
+A=[1, 2, 1, 3, 4, 3] and K = 3
+
+All windows of size K are
+
+[1, 2, 1]
+[2, 1, 3]
+[1, 3, 4]
+[3, 4, 3]
+
+So, we return an array [2, 3, 3, 2].
+```

Heaps And Maps/Distinct Numbers in Window/distinct_nums_in_window.cpp

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+//
+// Created by Islam, Abdullah Al Raqibul on 11/26/19.
+//
+
+vector<int> Solution::dNums(vector<int> &A, int B) {
+    map<int, int> cnt;
+    vector<int> v;
+    int i, j, k = B, sz = A.size(), cur = 0;
+
+    if(k > sz) return v;
+
+    for(i=0; i<sz; i+=1) {
+        if(i < k) {
+            if(cnt[A[i]] == 0) cur += 1;
+            cnt[A[i]] += 1;
+            if(i==k-1) {
+                v.push_back(cur);
+            }
+        }
+        else {
+            if(cnt[A[i-k]] == 1) cur -= 1;
+            cnt[A[i-k]] -= 1;
+            if(cnt[A[i]] == 0) cur += 1;
+            cnt[A[i]] += 1;
+
+            v.push_back(cur);
+        }
+    }
+    return v;
+}

Heaps And Maps/Merge K Sorted Lists/README.md

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+### Merge K Sorted Lists
+
+Asked in: [Flipkart](#) | [Amazon](#) | [Google](#)
+
+Merge k sorted linked lists and return it as one sorted list.
+
+Example :
+```
+1 -> 10 -> 20
+4 -> 11 -> 13
+3 -> 8 -> 9
+```
+will result in
+```
+1 -> 3 -> 4 -> 8 -> 9 -> 10 -> 11 -> 13 -> 20
+```

Heaps And Maps/Merge K Sorted Lists/merge_k_sorted_list.cpp

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+//
+// Created by Islam, Abdullah Al Raqibul on 11/26/19.
+//
+
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode(int x) : val(x), next(NULL) {}
+ * };
+ */
+ListNode* Solution::mergeKLists(vector<ListNode*> &lists) {
+    // Do not write main() function.
+    // Do not read input, instead use the arguments to the function.
+    // Do not print the output, instead return values as specified
+    // Still have a doubt. Checkout www.interviewbit.com/pages/sample_codes/ for more details
+
+    ListNode* head = new ListNode(0);
+
+    if(lists.size()==0) {
+        return NULL;
+    }
+
+    int sz = lists.size();
+    head->next = lists[0];
+    ListNode *p;
+    ListNode *q;
+
+    for(int i=1; i<sz; i+=1) {
+        p = head;
+        q = lists[i];
+        while(q) {
+            if(!p->next) {
+                p->next = q;
+                break;
+            }
+
+            if(p->next->val < q->val) {
+                p = p->next;
+            }
+            else {
+                ListNode *l = p->next;
+                p->next = q;
+                q = q->next;
+                p->next->next = l;
+                p = p->next;
+            }
+        }
+    }
+    return head->next;
+}