# Program for Worst Fit algorithm in Memory Management

Prerequisite : Partition allocation methods
Worst Fit allocates a process to the partition which is largest sufficient among the freely available partitions available in the main memory. If a large process comes at a later stage, then memory will not have space to accommodate it.

Example:

Input : blockSize[]   = {100, 500, 200, 300, 600};
processSize[] = {212, 417, 112, 426};
Output:
Process No.    Process Size    Block no.
1        212        5
2        417        2
3        112        5
4        426        Not Allocated

Implementation:
1- Input memory blocks and processes with sizes.
2- Initialize all memory blocks as free.
3- Start by picking each process and find the
maximum block size that can be assigned to
current process i.e., find max(bockSize[1],
blockSize[2],.....blockSize[n]) >
processSize[current], if found then assign
it to the current process.
5- If not then leave that process and keep checking
the further processes.

Below is implementation of above steps.

## C++

 // C++ implementation of worst - Fit algorithm #include using namespace std;   // Function to allocate memory to blocks as per worst fit // algorithm void worstFit(int blockSize[], int m, int processSize[],                                                   int n) {     // Stores block id of the block allocated to a     // process     int allocation[n];       // Initially no block is assigned to any process     memset(allocation, -1, sizeof(allocation));       // pick each process and find suitable blocks     // according to its size ad assign to it     for (int i=0; i= processSize[i])             {                 if (wstIdx == -1)                     wstIdx = j;                 else if (blockSize[wstIdx] < blockSize[j])                     wstIdx = j;             }         }           // If we could find a block for current process         if (wstIdx != -1)         {             // allocate block j to p[i] process             allocation[i] = wstIdx;               // Reduce available memory in this block.             blockSize[wstIdx] -= processSize[i];         }     }       cout << "\nProcess No.\tProcess Size\tBlock no.\n";     for (int i = 0; i < n; i++)     {         cout << "   " << i+1 << "\t\t" << processSize[i] << "\t\t";         if (allocation[i] != -1)             cout << allocation[i] + 1;         else            cout << "Not Allocated";         cout << endl;     } }   // Driver code int main() {     int blockSize[] = {100, 500, 200, 300, 600};     int processSize[] = {212, 417, 112, 426};     int m = sizeof(blockSize)/sizeof(blockSize[0]);     int n = sizeof(processSize)/sizeof(processSize[0]);       worstFit(blockSize, m, processSize, n);       return 0 ; }

## Java

 // Java implementation of worst - Fit algorithm   public class GFG  {     // Method to allocate memory to blocks as per worst fit     // algorithm     static void worstFit(int blockSize[], int m, int processSize[],                                                       int n)     {         // Stores block id of the block allocated to a         // process         int allocation[] = new int[n];                // Initially no block is assigned to any process         for (int i = 0; i < allocation.length; i++)             allocation[i] = -1;                // pick each process and find suitable blocks         // according to its size ad assign to it         for (int i=0; i= processSize[i])                 {                     if (wstIdx == -1)                         wstIdx = j;                     else if (blockSize[wstIdx] < blockSize[j])                         wstIdx = j;                 }             }                    // If we could find a block for current process             if (wstIdx != -1)             {                 // allocate block j to p[i] process                 allocation[i] = wstIdx;                        // Reduce available memory in this block.                 blockSize[wstIdx] -= processSize[i];             }         }                System.out.println("\nProcess No.\tProcess Size\tBlock no.");         for (int i = 0; i < n; i++)         {             System.out.print("   " + (i+1) + "\t\t" + processSize[i] + "\t\t");             if (allocation[i] != -1)                 System.out.print(allocation[i] + 1);             else                System.out.print("Not Allocated");             System.out.println();         }     }           // Driver Method     public static void main(String[] args)     {          int blockSize[] = {100, 500, 200, 300, 600};          int processSize[] = {212, 417, 112, 426};          int m = blockSize.length;          int n = processSize.length;                     worstFit(blockSize, m, processSize, n);     } }

## Python3

 # Python3 implementation of worst - Fit algorithm    # Function to allocate memory to blocks as  # per worst fit algorithm  def worstFit(blockSize, m, processSize, n):           # Stores block id of the block      # allocated to a process            # Initially no block is assigned      # to any process      allocation = [-1] * n           # pick each process and find suitable blocks      # according to its size ad assign to it      for i in range(n):                   # Find the best fit block for          # current process          wstIdx = -1        for j in range(m):             if blockSize[j] >= processSize[i]:                 if wstIdx == -1:                      wstIdx = j                  elif blockSize[wstIdx] < blockSize[j]:                      wstIdx = j           # If we could find a block for          # current process          if wstIdx != -1:                           # allocate block j to p[i] process              allocation[i] = wstIdx                # Reduce available memory in this block.              blockSize[wstIdx] -= processSize[i]       print("Process No. Process Size Block no.")     for i in range(n):         print(i + 1, "         ",                processSize[i], end = "     ")          if allocation[i] != -1:             print(allocation[i] + 1)          else:             print("Not Allocated")   # Driver code  if __name__ == '__main__':     blockSize = [100, 500, 200, 300, 600]      processSize = [212, 417, 112, 426]      m = len(blockSize)      n = len(processSize)        worstFit(blockSize, m, processSize, n)   # This code is contributed by PranchalK

## C#

 // C# implementation of worst - Fit algorithm  using System;   class GFG  {      // Method to allocate memory to blocks       // as per worst fit algorithm      static void worstFit(int []blockSize, int m,                          int []processSize, int n)      {          // Stores block id of the block allocated to a          // process          int []allocation = new int[n];                // Initially no block is assigned to any process          for (int i = 0; i < allocation.Length; i++)              allocation[i] = -1;                // pick each process and find suitable blocks          // according to its size ad assign to it          for (int i = 0; i < n; i++)          {              // Find the best fit block for current process              int wstIdx = -1;              for (int j = 0; j < m; j++)              {                  if (blockSize[j] >= processSize[i])                  {                      if (wstIdx == -1)                          wstIdx = j;                      else if (blockSize[wstIdx] < blockSize[j])                          wstIdx = j;                  }              }                    // If we could find a block for current process              if (wstIdx != -1)              {                  // allocate block j to p[i] process                  allocation[i] = wstIdx;                        // Reduce available memory in this block.                  blockSize[wstIdx] -= processSize[i];              }          }                Console.WriteLine("\nProcess No.\tProcess Size\tBlock no.");          for (int i = 0; i < n; i++)          {              Console.Write(" " + (i+1) + "\t\t\t" + processSize[i] + "\t\t\t");              if (allocation[i] != -1)                  Console.Write(allocation[i] + 1);              else                Console.Write("Not Allocated");              Console.WriteLine();          }      }            // Driver code     public static void Main(String[] args)      {          int []blockSize = {100, 500, 200, 300, 600};          int []processSize = {212, 417, 112, 426};          int m = blockSize.Length;          int n = processSize.Length;                    worstFit(blockSize, m, processSize, n);      }  }    // This code has been contributed by 29AjayKumar

## Javascript



Output
Process No.    Process Size    Block no.
1        212        5
2        417        2
3        112        5
4        426        Not Allocated

Time Complexity: O(N*M)  where N is processSize length and M is blockSize length.
Auxiliary Space: O(N)

Previous
Next