Problem: 2050E - Three Strings
Language: python

Solution 1 (runtime: 281 ms):
def min_changes(a, b, c):
    len_a = len(a)
    len_b = len(b)
    len_c = len(c)
    
    # Initialize the DP table
    dp = [[float('inf')] * (len_b + 1) for _ in range(len_a + 1)]
    dp[0][0] = 0  # Base case, no change needed for empty strings
    
    # Fill the DP table
    for i in range(len_a + 1):
        for j in range(len_b + 1):
            if i + j > len_c:
                continue
            if i < len_a and a[i] == c[i + j]:
                dp[i + 1][j] = min(dp[i + 1][j], dp[i][j])
            if j < len_b and b[j] == c[i + j]:
                dp[i][j + 1] = min(dp[i][j + 1], dp[i][j])
            if i < len_a and a[i] != c[i + j]:
                dp[i + 1][j] = min(dp[i + 1][j], dp[i][j] + 1)
            if j < len_b and b[j] != c[i + j]:
                dp[i][j + 1] = min(dp[i][j + 1], dp[i][j] + 1)
    
    return dp[len_a][len_b]

# Input
t = int(input())  # Number of test cases
for _ in range(t):
    a = input().strip()  # First string
    b = input().strip()  # Second string
    c = input().strip()  # Third string
    
    # Compute the result
    result = min_changes(a, b, c)
    
    # Output the result
    print(result)


Solution 2 (runtime: 280 ms):
# import sys
# sys.setrecursionlimit(2*(10**3))
# for _ in range(int(input())):
#     a = input()
#     b = input()
#     c = input()
#     dic = {}

#     def calculate(i,j,k,dic):
#         if (i,j,k) in dic:
#             return dic[(i,j,k)]
#         if i == len(a):
#             count = 0
#             while k <len(c):
#                 if c[k] != b[j]:
#                     count+=1
#                 k+=1
#                 j+=1
#             dic[(i,j,k)] = count
#             return count
#         if j == len(b):
#             count = 0
#             while k < len(c):
#                 if c[k] != a[i]:
#                     count+=1
#                 i+=1
#                 k+=1
#             dic[(i,j,k)] = count
#             return count 

#         if c[k]!=a[i] and c[k]!=b[j]:
#             count = 1 + min(calculate(i+1,j,k+1,dic),calculate(i,j+1,k+1,dic))
#         elif c[k]!=a[i] and c[k] == b[j]:
#             count = min(calculate(i,j+1,k+1,dic),calculate(i+1,j,k+1,dic)+1)
#         elif c[k]==a[i] and c[k] != b[j]:
#             count = min(calculate(i,j+1,k+1,dic)+1,calculate(i+1,j,k+1,dic))
#         else:
#             count = min(calculate(i+1,j,k+1,dic),calculate(i,j+1,k+1,dic))

#         dic[(i,j,k)] = count
#         return count    
            
#     print(calculate(0,0,0,dic))

for _ in range(int(input())):
    a = input()
    b = input()
    c = input()

    dp = [[float('inf')] * (len(b) + 1) for _ in range(len(a) + 1)]

    for i in range(len(a) + 1):
        for j in range(len(b) + 1):
            k = i + j
            if k > len(c):
                continue

            if i == 0 and j == 0:
                dp[i][j] = 0
            else:
                if i > 0 and c[k - 1] == a[i - 1]:
                    dp[i][j] = min(dp[i][j], dp[i - 1][j])
                if j > 0 and c[k - 1] == b[j - 1]:
                    dp[i][j] = min(dp[i][j], dp[i][j - 1])
                if i > 0 and c[k - 1] != a[i - 1]:
                    dp[i][j] = min(dp[i][j], dp[i - 1][j] + 1)
                if j > 0 and c[k - 1] != b[j - 1]:
                    dp[i][j] = min(dp[i][j], dp[i][j - 1] + 1)

    print(dp[len(a)][len(b)])