c++ - Worst fit algorithm

Question

I've created a code which demonstrates the First Fit Algorithm using an array of size 256 , the code displays a map showing how the memory is being stored according to the First Fit Algorithm, the code allows the user to delete a memory location too , I would like to create the same concept of my code but using the Worst Fit Algorithm , I've read many articles and understood how the Worst Fit Algorithm works but I can't think of a way so that my code works using the Worst Fit Algorithm , it's easier to use the First Fit than the Worst Fit on my code, could someone show me how to implement my code to use the Worst Fit Algorithm , would be appreciated a lot.

HERE'S THE CODE :

include <iostream>
#include <cmath>

using namespace std;

int PutInMemory(int memory[], int size) {

if (size < 1) cout << "Error!" << endl;
int firstSize = 0;
int j;
for (int i = 0; i < 256; i++) {
    if (memory[i] < 0 && abs(memory[i]) >= size) {
        j = i;
        firstSize += abs(memory[j]);
        break;
    }
}
if (firstSize < size) {
    cout << "Out of Memory";
    return 0;
}
if (j + size <= 256) {
    memory[j] = size;
    for (int i = j + 1; i < j + size; i++)
        memory[i] = 0;
    int i = j + size;
    int count = 0;
    while (memory[i] <= -1 && i < 256) {
        count++;
        i++;
    }
    if (count != 0) {
        memory[i - 1] = -count;
        memory[j + size] = -count;
    }
    return j;

}
else {
    cout << "Out of memory";
}

}


void DelSeg(int memory[], int n) {
int count = memory[n];
int prev = 0;
int next = count - 1;
int i = n + 1;
int pos = n;
if (memory[n - 1] < -1 && n != 0) {
    i += memory[n - 1];
    prev = -memory[n - 1];
    count -= memory[n - 1];
    pos = i;
}
while (true) {
    for (i; i < pos + count - 1; i++) {
        memory[i] = -1;
    }
    if (memory[i + 1] < -1) {
        count += -memory[i + 1] + 1;
        next = -memory[i + 1];
    }
    else {
        break;
    }
}

memory[n - prev] = 0 - count;
memory[n + next] = 0 - count;
}

void checkMemory(int memory[]) {
int countFreeSeg = 0;
int countFullSeg = 0;
int countFullMem = 0;
int countFreeMem = 0;

for (int i = 0; i < 256; i++) {
    if (memory[i] < 0) {
        if (memory[i] < 0) cout << "Beginning of the adress:" << i << ", ";
        int count = 0;
        while (memory[i] < 0 && i < 256) {
            count++;
            i++;
        }
        countFreeSeg++;
        cout << "Size = " << count << endl;
        countFreeMem += count;
        i--;
    }
}
cout << "Number of free processes = " << countFreeSeg << endl << endl;
cout << "Number of free memory = " << countFreeMem << endl << endl;


for (int i = 0; i < 256; i++) {
    if (memory[i] > 0) {
        cout << "Beginning adress: " << i << ", size - " << memory[i] << endl;
        countFullMem += memory[i];
        i += memory[i] - 1;
        countFullSeg++;
    }
}
cout << "Number of occupied processes = " << countFullSeg << endl;
cout << "Number of occupied memory = " << countFullMem << endl;
}

void print(int memory[]) {
for (int i = 0; i < 256; i++) {
    cout << memory[i] << " ";
}
}


int main()
{
int memory[256];
memory[0] = -256;
for (int i = 1; i < 256; i++) {
    memory[i] = -1;
}

while (true) {
    system("cls");
    cout << "1.Allocate Memory 
2.Free memory segment
3.Get information about the 
memory
4.Exit" << endl;
    int choice;
    cin >> choice;
    int m = 0;

    switch (choice)
    {
    case 1:
        system("cls");
        cout << "Enter the amount of memory to be entered:" << endl;
        cin >> m;
        cout << PutInMemory(memory, m) << endl;
        break;
    case 2:
        system("cls");
        cout << "Enter the starting address of the memory location:" << endl;
        cin >> m;
        DelSeg(memory, m);
        break;
    case 3:
        checkMemory(memory);
        print(memory);
        break;
    case 4:
        system("cls");
        exit(0);
        break;
    default:
        cout << "Incorrect entry" << endl;
        break;
    }
    system("pause");
}
}

Answer 1

Your code for FirstFit works by finding the first block of memory large enough to hold your requested allocation. You stop as soon as you find any block that will fit.

  int firstSize = 0;
  int j;
  for (int i = 0; i < 256; i++) {
    if (memory[i] < 0 && abs(memory[i]) >= size) {
      j = i;
      firstSize += abs(memory[j]);
      break;
    }
  }
  if (firstSize < size) {
    cout << "Out of Memory";
    return 0;
  }

For WorstFit, you simply need to find the largest available contiguous block of memory and allocate that, if it's large enough.

  int worstSize = 0;
  int j;
  for (int i = 0; i < 256; i++) {
    if (memory[i] < 0 && abs(memory[i]) >= worstSize) {
      j = i;
      worstSize = abs(memory[j]);
    }
  }
  if (worstSize < size) {
    cout << "Out of Memory";
    return 0;
  }