Update RotatedSortedArraySearch.cpp

Binary-Search/RotatedSortedArraySearch.cpp

@@ -1,105 +1,18 @@
 // https://www.interviewbit.com/problems/rotated-sorted-array-search/
 
-int search1(const vector<int> &arr, int low, int high, int B) 
-{ 
-    if (low > high) return -1; 
-
-    int mid = (low) + (high-low)/2; 
-    if (arr[mid] == B) return mid; 
-
-    if (arr[low] <= arr[mid]) 
-    { 
-        if (B >= arr[low] && B <= arr[mid]) 
-        return search1(arr, low, mid-1, B); 
-
-        return search1(arr, mid+1, high, B); 
-    } 
-
-    else if (arr[mid] <= arr[high])
-    {
-    if (B >= arr[mid] && B <= arr[high]) 
-        return search1(arr, mid+1, high, B); 
-
-    return search1(arr, low, mid-1, B); 
-    }
-} 
-
-
 int Solution::search(const vector<int> &A, int B) {
-
-   int n = A.size();
-   int i = search1(A, 0, n-1, B); 
-
-    if (i != -1) 
-    return i;
-    else
-    return -1;
-
-}
-
-/*
-int findPivot(const vector<int> &A){
-    int start = 0;
-    int end = A.size()-1;
-    int mid;
     int n = A.size();
-    while(start <= end){
-        mid = start + (end-start)/2;
-        int next = (mid+1)%n;
-        int prev = (mid-1+n)%n;
-        if(A[start] <= A[end]){
-            return start;
-        }
-        else if((A[mid] <= A[prev]) && (A[mid] <= A[next])){
-            return mid;
-        }
-        else if(A[mid] <= A[end]){
-            end = mid-1;
-        }
-        else{ // A[mid] >= A[start]
-            start = mid+1;
-        }
-    }
-    return -1;
-}
-
-int binarySearch(const vector<int> &A, int start, int end, int key){
-    int mid;
-    while(start <= end){
-        mid = start + (end-start)/2;
-        if(A[mid] == key){
-            return mid;
-        }
-        else if(A[mid] > key){
-            end = mid-1;
-        }
-        else{ // A[mid] < key
-            start = mid+1;
+    int low = 0, high = n-1;
+    while(low<=high){
+        int mid = low + (high-low)/2;
+        if(A[mid] == B) return mid;
+        else if(A[0]<=A[mid]){//i.e. left part is sorted
+            if(A[0]<=B && B < A[mid]) high = mid-1;//B lies on left part
+            else low = mid+1;
+        }else{//right part is sorted
+            if(A[mid] < B && B<=A[n-1]) low = mid+1;//B lies on right part
+            else high = mid-1;
         }
     }
     return -1;
 }
-
-int Solution::search(const vector<int> &A, int B) {
-    // 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
-
-    int pivot = findPivot(A);
-    if(B == A[pivot]){
-        return pivot;
-    }
-
-    int result = binarySearch(A, 0, pivot-1, B);
-
-    if(result == -1){
-        return binarySearch(A, pivot+1, A.size()-1, B);    
-    }
-
-    return result;
-
-    // B < A[pivot]
-
-}
-*/

Heaps-and-Maps/MergeKSortedLists.cpp

@@ -1,5 +1,3 @@
-// https://www.interviewbit.com/problems/merge-k-sorted-lists/
-
 /**
  * Definition for singly-linked list.
  * struct ListNode {
@@ -8,49 +6,26 @@
  *     ListNode(int x) : val(x), next(NULL) {}
  * };
  */
+struct Compare
+{
+    bool operator()(ListNode* const& a, ListNode* const& b)
+    {
+        return a->val > b->val;
+    }
+};
 ListNode* Solution::mergeKLists(vector<ListNode*> &A) {
-    // 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
-
-    map<int, int> myMap;
-
-    for(int i = 0; i < A.size(); i++){
-        ListNode* curr = A[i];
-        while(curr != NULL){
-            int temp = curr->val;
-            if(myMap.find(temp) != myMap.end()){
-                myMap[temp]++;
-            }
-            else{
-                myMap[temp] = 1;
-            }
-            curr = curr->next;
-        }
+    priority_queue<ListNode*, vector<ListNode*>, Compare>pq;
+    if(A.empty()) return NULL;
+    ListNode* head = new ListNode(0);
+    ListNode* curr = head;
+    for(auto i = 0; i < A.size(); i++){
+        pq.emplace(A[i]);
     }
-
-    auto it = myMap.begin();
-
-    ListNode* head = NULL;
-    ListNode* curr = NULL;
-
-    while(it != myMap.end()){
-        while(it->second != 0){
-            ListNode* list = new ListNode(it->first);
-            if(head == NULL){
-                head = list;
-                curr = list;
-            }
-            else{
-                curr->next = list;
-                curr = curr->next;
-            }
-            it->second--;
-        }
-        it++;
+    while (!pq.empty()){
+        curr->next = pq.top();
+        pq.pop();
+        curr = curr->next;
+        if(curr->next) pq.emplace(curr->next);
     }
-
-    return head;
-
+    return head->next;
 }