Create solution_rishita.py

added one more optimised solution

Author: rishita-ganguly

solution_rishita.py

@@ -0,0 +1,48 @@
+import hashlib
+import json
+import time
+
+class Block:
+    def __init__(self, index, previous_hash, timestamp, data, hash):
+        self.index = index
+        self.previous_hash = previous_hash
+        self.timestamp = timestamp
+        self.data = data
+        self.hash = hash
+
+def calculate_hash(index, previous_hash, timestamp, data):
+    value = str(index) + str(previous_hash) + str(timestamp) + json.dumps(data)
+    return hashlib.sha256(value.encode('utf-8')).hexdigest()
+
+def create_genesis_block():
+    return Block(0, "0", int(time.time()), [], "0000000000000000000000000000000000000000000000000000000000000000")
+
+def create_new_block(previous_block, data):
+    index = previous_block.index + 1
+    timestamp = int(time.time())
+    hash = calculate_hash(index, previous_block.hash, timestamp, data)
+    return Block(index, previous_block.hash, timestamp, data, hash)
+
+# Initialize blockchain with a genesis block
+blockchain = [create_genesis_block()]
+current_block = blockchain[-1]
+
+# Example data for lost and found system
+lost_item_data = {
+    "item_name": "Phone",
+    "description": "iPhone X",
+    "owner_name": "Alice",
+    "contact_info": "123-456-7890"
+}
+
+# Add a lost item to the blockchain
+current_block = create_new_block(current_block, lost_item_data)
+blockchain.append(current_block)
+
+# Print the blockchain
+for block in blockchain:
+    print(f"Index: {block.index}")
+    print(f"Previous Hash: {block.previous_hash}")
+    print(f"Timestamp: {block.timestamp}")
+    print(f"Data: {json.dumps(block.data)}")
+    print(f"Hash: {block.hash}\n")