add khushal87 binary-search-code

.vscode/settings.json

@@ -4,6 +4,15 @@
  "vector": "cpp",
  "ostream": "cpp",
  "deque": "cpp",
- "string": "cpp"
+ "string": "cpp",
+ "array": "cpp",
+ "forward_list": "cpp",
+ "list": "cpp",
+ "unordered_map": "cpp",
+ "unordered_set": "cpp",
+ "string_view": "cpp",
+ "initializer_list": "cpp",
+ "regex": "cpp",
+ "valarray": "cpp"
  }
 }

Binary Search/allocate_min_number_of_pages.cpp

@@ -0,0 +1,43 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+bool isValid(int arr[], int n, int k, int mx)
+{
+ int stud = 1;
+ int sum = 0;
+ for (int i = 0; i < n; i++)
+ {
+ sum += arr[i];
+ if (sum > mx)
+ {
+ stud++;
+ sum = arr[i];
+ }
+ if (stud > k)
+ return false;
+ }
+ return true;
+}
+
+int allocateMinNumberOfPage(int arr[], int n, int k)
+{
+ if (n < k)
+ return -1;
+ int start = *max_element(arr, arr + n);
+ int end = accumulate(arr, arr + n, 0);
+ int result = -1;
+ while (start <= end)
+ {
+ int mid = start + (end - start) / 2;
+ if (isValid(arr, n, k, mid))
+ {
+ result = mid;
+ end = mid - 1;
+ }
+ else
+ {
+ start = mid + 1;
+ }
+ }
+ return result;
+}

Binary Search/find_a_element_in_rotated_sorted_array.cpp

@@ -1,7 +1,7 @@
 #include <bits/stdc++.h>
 using namespace std;
 
-int binarySearch(int arr[], int n, int start, int end, int el)
+int ascBinarySearch(vector<int> &arr, int n, int start, int end, int el)
 {
  if (start <= end)
  {
@@ -12,17 +12,17 @@ int binarySearch(int arr[], int n, int start, int end, int el)
  }
  else if (arr[mid] < el)
  {
- return binarySearch(arr, n, mid + 1, end, el);
+ return ascBinarySearch(arr, n, mid + 1, end, el);
  }
  else
  {
- return binarySearch(arr, n, start, mid - 1, el);
+ return ascBinarySearch(arr, n, start, mid - 1, el);
  }
  }
  return -1;
 }
 
-int pivotIdx(int arr[], int n)
+int pivotIdx(vector<int> &arr, int n)
 {
  if (arr[0] < arr[n - 1])
  return 0;
@@ -58,11 +58,12 @@ int pivotIdx(int arr[], int n)
  }
 }
 
-int solve(int arr[], int n, int el)
+int solve(vector<int> &arr, int n, int el)
 {
+ int n = arr.size();
  int pdx = pivotIdx(arr, n);
- int idx1 = binarySearch(arr, n, 0, pdx - 1, el);
- int idx2 = binarySearch(arr, n, pdx, n - 1, el);
+ int idx1 = ascBinarySearch(arr, n, 0, pdx - 1, el);
+ int idx2 = ascBinarySearch(arr, n, pdx, n - 1, el);
  if (idx1 == -1 && idx2 == -1)
  return -1;
  else

Binary Search/maximum_in_bitonic_array.cpp

@@ -0,0 +1,50 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+//same as finding peak element
+int peakElement(int arr[], int n)
+{
+ int start = 0;
+ int end = n - 1;
+ while (start <= end)
+ {
+ int mid = start + (end - start) / 2;
+ if (mid > 0 && mid < n - 1)
+ {
+ if (arr[mid] > arr[mid - 1] && arr[mid] > arr[mid + 1])
+ {
+ return mid;
+ }
+ else if (arr[mid - 1] > arr[mid])
+ {
+ end = mid - 1;
+ }
+ else
+ {
+ start = mid + 1;
+ }
+ }
+ else if (mid == 0)
+ {
+ if (arr[mid + 1] < arr[mid])
+ {
+ return mid;
+ }
+ else
+ {
+ return mid + 1;
+ }
+ }
+ else if (mid == n - 1)
+ {
+ if (arr[mid] > arr[mid - 1])
+ {
+ return mid;
+ }
+ else
+ {
+ return mid - 1;
+ }
+ }
+ }
+}

Binary Search/peak_element.cpp

@@ -0,0 +1,49 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int peakElement(int arr[], int n)
+{
+ int start = 0;
+ int end = n - 1;
+ while (start <= end)
+ {
+ int mid = start + (end - start) / 2;
+ if (mid > 0 && mid < n - 1)
+ {
+ if (arr[mid] > arr[mid - 1] && arr[mid] > arr[mid + 1])
+ {
+ return mid;
+ }
+ else if (arr[mid - 1] > arr[mid])
+ {
+ end = mid - 1;
+ }
+ else
+ {
+ start = mid + 1;
+ }
+ }
+ else if (mid == 0)
+ {
+ if (arr[mid + 1] < arr[mid])
+ {
+ return mid;
+ }
+ else
+ {
+ return mid + 1;
+ }
+ }
+ else if (mid == n - 1)
+ {
+ if (arr[mid] > arr[mid - 1])
+ {
+ return mid;
+ }
+ else
+ {
+ return mid - 1;
+ }
+ }
+ }
+}

Binary Search/search_in_bitonic_array.cpp

@@ -0,0 +1,113 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int ascBinarySearch(vector<int> &arr, int n, int start, int end, int el)
+{
+ if (start <= end)
+ {
+ int mid = start + (end - start) / 2;
+ if (arr[mid] == el)
+ {
+ return mid;
+ }
+ else if (arr[mid] < el)
+ {
+ return ascBinarySearch(arr, n, mid + 1, end, el);
+ }
+ else
+ {
+ return ascBinarySearch(arr, n, start, mid - 1, el);
+ }
+ }
+ return -1;
+}
+
+int descBinarySearch(vector<int> &arr, int n, int start, int end, int el)
+{
+ if (start <= end)
+ {
+ int mid = start + (end - start) / 2;
+ if (arr[mid] == el)
+ {
+ return mid;
+ }
+ else if (arr[mid] > el)
+ {
+ return descBinarySearch(arr, n, mid + 1, end, el);
+ }
+ else
+ {
+ return descBinarySearch(arr, n, start, mid - 1, el);
+ }
+ }
+ return -1;
+}
+
+//same as finding peak element
+int peakElement(vector<int> &arr, int n)
+{
+ int start = 0;
+ int end = n - 1;
+ while (start <= end)
+ {
+ int mid = start + (end - start) / 2;
+ if (mid > 0 && mid < n - 1)
+ {
+ if (arr[mid] > arr[mid - 1] && arr[mid] > arr[mid + 1])
+ {
+ return mid;
+ }
+ else if (arr[mid - 1] > arr[mid])
+ {
+ end = mid - 1;
+ }
+ else
+ {
+ start = mid + 1;
+ }
+ }
+ else if (mid == 0)
+ {
+ if (arr[mid + 1] < arr[mid])
+ {
+ return mid;
+ }
+ else
+ {
+ return mid + 1;
+ }
+ }
+ else if (mid == n - 1)
+ {
+ if (arr[mid] > arr[mid - 1])
+ {
+ return mid;
+ }
+ else
+ {
+ return mid - 1;
+ }
+ }
+ }
+}
+
+int solve(vector<int> &arr, int el)
+{
+ int n = arr.size();
+ int pdx = peakElement(arr, n);
+ int idx1 = ascBinarySearch(arr, n, 0, pdx - 1, el);
+ int idx2 = descBinarySearch(arr, n, pdx, n - 1, el);
+ if (idx1 == -1 && idx2 == -1)
+ return -1;
+ else
+ {
+ if (idx1 == -1)
+ {
+ return idx2;
+ }
+ if (idx2 == -1)
+ {
+ return idx1;
+ }
+ }
+}

Binary Search/search_in_row_column_sorted_array.cpp

@@ -0,0 +1,24 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+pair<int, int> index(vector<vector<int>> &arr, int n, int m, int el)
+{
+ int i = 0;
+ int j = m - 1;
+ while ((i >= 0 && i < n) && (j >= 0 && j < m))
+ {
+ if (arr[i][j] == el)
+ {
+ return {i, j};
+ }
+ else if (arr[i][j] > el)
+ {
+ j--;
+ }
+ else
+ {
+ i++;
+ }
+ }
+ return {-1, -1};
+}