Added LRU and optimal code (a7).

Codes/Python version/Assignment-A5 (CPU Scheduling)/FCFS.py

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+def fcfs_scheduling(processes, n):
+    processes.sort(key=lambda x: x[1])
+    completion_time = 0
+    waiting_time = []
+    turnaround_time = []
+
+    for process in processes:
+        pid, arrival_time, burst_time = process
+
+        if completion_time < arrival_time:
+            completion_time = arrival_time
+
+        completion_time += burst_time
+        turnaround_time.append(completion_time - arrival_time)
+        waiting_time.append(completion_time - arrival_time - burst_time)
+
+    print("\nFCFS Scheduling:")
+    for i, process in enumerate(processes):
+        print(f"Process {process[0]}: Waiting Time = {waiting_time[i]}, Turnaround Time = {turnaround_time[i]}")
+
+# Input: Process ID, Arrival Time, Burst Time
+processes = [[1, 0, 5], [2, 1, 3], [3, 2, 8], [4, 3, 6]]
+fcfs_scheduling(processes, len(processes))

Codes/Python version/Assignment-A5 (CPU Scheduling)/Priority.py

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+def priority_scheduling(processes, n):
+    processes.sort(key=lambda x: (x[2], x[1]))
+    completion_time = 0
+    waiting_time = []
+    turnaround_time = []
+
+    for process in processes:
+        pid, arrival_time, priority, burst_time = process
+
+        if completion_time < arrival_time:
+            completion_time = arrival_time
+
+        completion_time += burst_time
+        turnaround_time.append(completion_time - arrival_time)
+        waiting_time.append(completion_time - arrival_time - burst_time)
+
+    print("\nPriority (Non-Preemptive) Scheduling:")
+    for i, process in enumerate(processes):
+        print(f"Process {process[0]}: Waiting Time = {waiting_time[i]}, Turnaround Time = {turnaround_time[i]}")
+
+# Input: Process ID, Arrival Time, Priority, Burst Time
+processes = [[1, 0, 1, 5], [2, 1, 3, 3], [3, 2, 2, 8], [4, 3, 4, 6]]
+priority_scheduling(processes, len(processes))

Codes/Python version/Assignment-A5 (CPU Scheduling)/Round Robin.py

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+def round_robin(processes, n, quantum):
+    remaining_time = [bt for _, _, bt in processes]
+    t = 0
+    waiting_time = [0] * n
+    turnaround_time = [0] * n
+    complete = [False] * n
+
+    while True:
+        done = True
+
+        for i in range(n):
+            if remaining_time[i] > 0:
+                done = False
+
+                if remaining_time[i] > quantum:
+                    t += quantum
+                    remaining_time[i] -= quantum
+                else:
+                    t += remaining_time[i]
+                    waiting_time[i] = t - processes[i][2] - processes[i][1]
+                    remaining_time[i] = 0
+
+        if done:
+            break
+
+    for i in range(n):
+        turnaround_time[i] = processes[i][2] + waiting_time[i]
+
+    print("\nRound Robin (Preemptive) Scheduling:")
+    for i, process in enumerate(processes):
+        print(f"Process {process[0]}: Waiting Time = {waiting_time[i]}, Turnaround Time = {turnaround_time[i]}")
+
+# Input: Process ID, Arrival Time, Burst Time
+processes = [[1, 0, 10], [2, 1, 4], [3, 2, 5], [4, 3, 3]]
+quantum = 2
+round_robin(processes, len(processes), quantum)

Codes/Python version/Assignment-A5 (CPU Scheduling)/SJF.py

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+import sys
+
+def sjf_preemptive(processes, n):
+    remaining_time = [bt for _, _, bt in processes]
+    complete = 0
+    t = 0
+    minm = sys.maxsize
+    shortest = 0
+    finish_time = 0
+    check = False
+    waiting_time = [0] * n
+    turnaround_time = [0] * n
+
+    while complete != n:
+        for j in range(n):
+            if processes[j][1] <= t and remaining_time[j] < minm and remaining_time[j] > 0:
+                minm = remaining_time[j]
+                shortest = j
+                check = True
+
+        if not check:
+            t += 1
+            continue
+
+        remaining_time[shortest] -= 1
+        minm = remaining_time[shortest] if remaining_time[shortest] > 0 else sys.maxsize
+
+        if remaining_time[shortest] == 0:
+            complete += 1
+            check = False
+            finish_time = t + 1
+            waiting_time[shortest] = finish_time - processes[shortest][2] - processes[shortest][1]
+
+            if waiting_time[shortest] < 0:
+                waiting_time[shortest] = 0
+
+        t += 1
+
+    for i in range(n):
+        turnaround_time[i] = processes[i][2] + waiting_time[i]
+
+    print("\nSJF (Preemptive) Scheduling:")
+    for i, process in enumerate(processes):
+        print(f"Process {process[0]}: Waiting Time = {waiting_time[i]}, Turnaround Time = {turnaround_time[i]}")
+
+# Input: Process ID, Arrival Time, Burst Time
+processes = [[1, 0, 8], [2, 1, 4], [3, 2, 9], [4, 3, 5]]
+sjf_preemptive(processes, len(processes))

Codes/Python version/Assignment-A6 (Memory placement)/Best Fit.py

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+def best_fit(memory_blocks, process_sizes):
+    allocation = [-1] * len(process_sizes)
+
+    for i in range(len(process_sizes)):
+        best_idx = -1
+        best_size = float('inf')
+
+        for j in range(len(memory_blocks)):
+            if memory_blocks[j] >= process_sizes[i] and memory_blocks[j] - process_sizes[i] < best_size:
+                best_size = memory_blocks[j] - process_sizes[i]
+                best_idx = j
+
+        if best_idx != -1:
+            allocation[i] = best_idx
+            memory_blocks[best_idx] -= process_sizes[i]
+
+    print("\nBest Fit Allocation:")
+    for i in range(len(process_sizes)):
+        if allocation[i] != -1:
+            print(f"Process {i+1} allocated to Block {allocation[i]+1}")
+        else:
+            print(f"Process {i+1} not allocated")
+
+# Example Memory Blocks and Process Sizes
+memory_blocks = [100, 500, 200, 300, 600]
+process_sizes = [212, 417, 112, 426]
+
+best_fit(memory_blocks, process_sizes)

Codes/Python version/Assignment-A6 (Memory placement)/First Fit.py

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+def first_fit(memory_blocks, process_sizes):
+    allocation = [-1] * len(process_sizes)
+
+    for i in range(len(process_sizes)):
+        for j in range(len(memory_blocks)):
+            if memory_blocks[j] >= process_sizes[i]:
+                allocation[i] = j
+                memory_blocks[j] -= process_sizes[i]
+                break
+
+    print("\nFirst Fit Allocation:")
+    for i in range(len(process_sizes)):
+        if allocation[i] != -1:
+            print(f"Process {i+1} allocated to Block {allocation[i]+1}")
+        else:
+            print(f"Process {i+1} not allocated")
+
+# Example Memory Blocks and Process Sizes
+memory_blocks = [100, 500, 200, 300, 600]
+process_sizes = [212, 417, 112, 426]
+
+first_fit(memory_blocks, process_sizes)

Codes/Python version/Assignment-A6 (Memory placement)/Next Fit.py

@@ -0,0 +1,25 @@
+def next_fit(memory_blocks, process_sizes):
+    allocation = [-1] * len(process_sizes)
+    next_index = 0
+
+    for i in range(len(process_sizes)):
+        while next_index < len(memory_blocks):
+            if memory_blocks[next_index] >= process_sizes[i]:
+                allocation[i] = next_index
+                memory_blocks[next_index] -= process_sizes[i]
+                next_index = (next_index + 1) % len(memory_blocks)  # Move to next block
+                break
+            next_index += 1
+
+    print("\nNext Fit Allocation:")
+    for i in range(len(process_sizes)):
+        if allocation[i] != -1:
+            print(f"Process {i+1} allocated to Block {allocation[i]+1}")
+        else:
+            print(f"Process {i+1} not allocated")
+
+# Example Memory Blocks and Process Sizes
+memory_blocks = [100, 500, 200, 300, 600]
+process_sizes = [212, 417, 112, 426]
+
+next_fit(memory_blocks, process_sizes)

Codes/Python version/Assignment-A6 (Memory placement)/Worst Fit.py

@@ -0,0 +1,28 @@
+def worst_fit(memory_blocks, process_sizes):
+    allocation = [-1] * len(process_sizes)
+
+    for i in range(len(process_sizes)):
+        worst_idx = -1
+        worst_size = -1
+
+        for j in range(len(memory_blocks)):
+            if memory_blocks[j] >= process_sizes[i] and memory_blocks[j] > worst_size:
+                worst_size = memory_blocks[j]
+                worst_idx = j
+
+        if worst_idx != -1:
+            allocation[i] = worst_idx
+            memory_blocks[worst_idx] -= process_sizes[i]
+
+    print("\nWorst Fit Allocation:")
+    for i in range(len(process_sizes)):
+        if allocation[i] != -1:
+            print(f"Process {i+1} allocated to Block {allocation[i]+1}")
+        else:
+            print(f"Process {i+1} not allocated")
+
+# Example Memory Blocks and Process Sizes
+memory_blocks = [100, 500, 200, 300, 600]
+process_sizes = [212, 417, 112, 426]
+
+worst_fit(memory_blocks, process_sizes)

Codes/Python version/Assignment-A7 (Page replacement)/LRU.py

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+class LRU:
+    def __init__(self, capacity):
+        self.capacity = capacity
+        self.cache = {}
+        self.order = []
+
+    def refer(self, page):
+        if page not in self.cache:
+            if len(self.cache) >= self.capacity:
+                lru_page = self.order.pop(0)  # Remove least recently used page
+                del self.cache[lru_page]
+        else:
+            self.order.remove(page)  # Remove page to update its order
+        self.cache[page] = True
+        self.order.append(page)
+
+    def display(self):
+        print("Current Pages in Memory (LRU):", list(self.cache.keys()))
+
+# Simulate LRU
+def lru_simulation(pages, capacity):
+    lru = LRU(capacity)
+    for page in pages:
+        lru.refer(page)
+        lru.display()
+
+# Example Pages and Capacity
+pages = [7, 0, 1, 2, 0, 3, 0, 4]
+capacity = 3
+print("LRU Page Replacement Simulation:")
+lru_simulation(pages, capacity)

Codes/Python version/Assignment-A7 (Page replacement)/Optimal.py

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+class Optimal:
+    def __init__(self, capacity):
+        self.capacity = capacity
+        self.cache = []
+
+    def refer(self, page, future):
+        if page not in self.cache:
+            if len(self.cache) < self.capacity:
+                self.cache.append(page)
+            else:
+                farthest_page = self.find_farthest_page(future)
+                index = self.cache.index(farthest_page)
+                self.cache[index] = page
+
+    def find_farthest_page(self, future):
+        farthest = -1
+        farthest_page = None
+        for page in self.cache:
+            if page not in future:
+                return page
+            try:
+                index = future.index(page)
+                if index > farthest:
+                    farthest = index
+                    farthest_page = page
+            except ValueError:
+                continue
+        return farthest_page
+
+    def display(self):
+        print("Current Pages in Memory (Optimal):", self.cache)
+
+# Simulate Optimal Page Replacement
+def optimal_simulation(pages, capacity):
+    optimal = Optimal(capacity)
+    for i in range(len(pages)):
+        optimal.refer(pages[i], pages[i + 1:])
+        optimal.display()
+
+# Example Pages and Capacity
+pages = [7, 0, 1, 2, 0, 3, 0, 4]
+capacity = 3
+print("\nOptimal Page Replacement Simulation:")
+optimal_simulation(pages, capacity)