Added all DAA in python

DAA/A3.py

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+# Fractional Knapsack using Greedy Method
+
+class Item:
+    def __init__(self, value, weight):
+        self.value = value
+        self.weight = weight
+
+def fractional_knapsack(items, capacity):
+    # Step 1: Sort items by value/weight ratio (descending)
+    items.sort(key=lambda x: x.value / x.weight, reverse=True)
+
+    total_value = 0.0  # total value in knapsack
+    remaining_capacity = capacity
+
+    # Step 2: Pick items greedily
+    for item in items:
+        if remaining_capacity >= item.weight:
+            # take full item
+            total_value += item.value
+            remaining_capacity -= item.weight
+        else:
+            # take fractional part
+            fraction = remaining_capacity / item.weight
+            total_value += item.value * fraction
+            break  # knapsack is full
+
+    return total_value
+
+# Example usage
+if __name__ == "__main__":
+    values = [60, 100, 120]
+    weights = [10, 20, 30]
+    capacity = 50
+
+    items = [Item(v, w) for v, w in zip(values, weights)]
+    max_value = fractional_knapsack(items, capacity)
+
+    print("Maximum value in Knapsack =", max_value)