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Author: Saptarshi-prog

Week 5/Edit distance.py

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+import numpy as np
+import sys
+
+
+def edit_distance(s, t):
+    temp = np.zeros(shape=(len(s) + 1, len(t) + 1), dtype=int)
+
+    for i in range(len(s)+1):
+        temp[i, 0] = i
+    for i in range(len(t)+1):
+        temp[0, i] = i
+
+    for i in range(1, len(s) + 1):
+        for j in range(1, len(t) + 1):
+            if s[i - 1] == t[j - 1]:
+                temp[i, j] = temp[i - 1, j - 1]
+            else:
+                temp[i, j] = 1 + min(temp[i - 1, j], temp[i - 1, j - 1], temp[i, j - 1])
+
+    return (temp[len(s), len(t)])
+
+
+if __name__ == "__main__":
+    input = sys.stdin.read()
+    input = list(map(str, input.split('\n')))
+    # print(edit_distance(input(), input()))
+    print(edit_distance(input[0], input[1]))

Week 5/Moneychange.py

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+import math
+
+money = int(input())
+denominations = [1, 3, 4]
+minCoins = [0] + [math.inf]*money
+
+for i in range(1, money+1):
+    for j in denominations:
+        if i>=j:
+            coins = minCoins[i-j]+1
+            if coins < minCoins[i]:
+                minCoins[i] = coins
+
+print(minCoins[money])

Week 5/Primitive Calculator.py

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+import math
+
+n = int(input())
+
+# number of operations required for getting 0, 1, 2,.. , n
+num_operations = [0, 0] + [math.inf]*(n-1)
+
+for i in range(2, n+1):
+    temp1, temp2, temp3 = [math.inf]*3
+
+    temp1 = num_operations[i-1] + 1 
+    if i%2 == 0: temp2 = num_operations[i//2] + 1
+    if i%3 == 0: temp3 = num_operations[i//3] + 1
+    min_ops = min(temp1, temp2, temp3)
+    num_operations[i] = min_ops
+
+print(num_operations[n])
+
+# Backtracking the numbers leading to n
+nums = [n]
+while n!=1:
+    if n%3 ==0 and num_operations[n]-1 == num_operations[n//3]:
+        nums += [n//3]
+        n = n//3
+    elif n%2 ==0 and num_operations[n]-1 == num_operations[n//2]:
+        nums += [n//2]
+        n = n//2
+    else:
+        nums += [n-1]
+        n = n - 1
+
+print(' '.join([str(i) for i in nums][::-1]))