Added the Allocate Minimum No. of Pages.cpp

Author: geekySapien

DSA 450 GFG/AllocateMinimumNumberOfPages.cpp

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+//Problem Statement Link https://practice.geeksforgeeks.org/problems/allocate-minimum-number-of-pages0937/1
+
+//Example Test Case
+//Input
+//  n        -> Size of Array
+//  arr[]    -> Array
+//  m        -> No. of Students
+/*
+
+n = 4
+arr[] = {12,34,67,90}
+m = 2
+
+Here possible allocations can be: 
+
+1. {12}, {34, 67, 90} i.e one student reads 12 pages and another 
+   reads 191 (34+67+91) pages, so here maximum is 191
+
+2. {12,34}, {67,90} i.e one student reads  46 (12+34) pages and another 
+   reads 158 (67+91) pages, so here maximum is 158
+
+3. {12,34, 67} i.e one student reads  113 (12+34+67) pages and another 
+   reads 91 pages, so here maximum is 113
+
+Out of three cases minimum maximum is 113 so that would be printed in the output
+
+*/
+
+//The program for this problem goes as follows
+
+//Header file to include all header files of C++
+#include <bits/stdc++.h>
+using namespace std;
+
+class Solution
+{
+public:
+    //Function to find minimum number of pages.
+    int findPages(int arr[], int n, int m)
+    {
+        // we store the maximum of array in min i.e a student can read atleast
+        // one book (with max pages) from the given array of books
+        int min = findMax(arr, n);
+
+        //we store suma of all books in max variable
+        int max = findSum(arr, n);
+
+        // ans is minimum of maximum pages that can be assigned to a student
+        int ans = -1;
+
+        //Applying Binary Search
+        while (min <= max)
+        {
+            int mid = (min + max) / 2;
+
+            //calling isFeaible function to check whether we can have mid as the
+            //minimum maximum no. of pages possible
+
+            //If yes, assign mid to ans and check further with smaller values.
+            if (isFeasible(arr, n, m, mid))
+            {
+                ans = mid;
+                max = mid - 1;
+            }
+
+            //If no, increment the min and check further with larger values
+            else
+            {
+                min = mid + 1;
+            }
+        }
+
+        //return the final ans
+        return ans;
+    }
+
+    // A utility function to find sum of array elements
+    static int findSum(int arr[], int n)
+    {
+        int sum = 0;
+        for (int i = 0; i < n; i++)
+        {
+            sum += arr[i];
+        }
+        return sum;
+    }
+
+    // A utility function to find max of all array elements
+    static int findMax(int arr[], int n)
+    {
+        int max = arr[0];
+        for (int i = 1; i < n; i++)
+        {
+            if (max < arr[i])
+                max = arr[i];
+        }
+        return max;
+    }
+
+    // A function to check wheter it is feasible to allocate 'mid' no of pages
+    // to m students
+    static bool isFeasible(int arr[], int n, int m, int mid)
+    {
+        int student = 1;
+        int sum = 0;
+
+        //Iterating over the array elements
+        for (int i = 0; i < n; i++)
+        {
+            //if the current sum is less than mid, add it into the sum variable
+            if (sum + arr[i] <= mid)
+            {
+                sum += arr[i];
+            }
+
+            //else increment the number of students and reassign sum with array element
+            else
+            {
+                student++;
+                sum = arr[i];
+            }
+        }
+
+        // finally return whether no of students are less than or equal to m
+        return (student <= m);
+    }
+};
+
+// Main Function
+int main()
+{
+
+    // t -> No of Test Cases
+    // n -> Size of Array
+    // A -> Array
+    // m -> No of Students
+    int t;
+    cin >> t;
+    while (t--)
+    {
+        int n;
+        cin >> n;
+        int A[n];
+
+        //Input Array Elements
+        for (int i = 0; i < n; i++)
+        {
+            cin >> A[i];
+        }
+        int m;
+        cin >> m;
+
+        //making object of class
+        Solution ob;
+
+        //calling findPages Method and displaying the final ans
+        cout << ob.findPages(A, n, m) << endl;
+    }
+    return 0;
+}