1. 문제

9521번

2. 풀이

a = input()
b = input()

a = ' ' + a
b = ' ' + b

dp = [[0 for _ in range(len(a))] for _ in range(len(b))]

for j in range(1, len(b)):
    for i in range(1, len(a)):
        if b[j] == a[i]:
            dp[j][i] = dp[j-1][i-1] + 1
        else:
            dp[j][i] = max(dp[j-1][i], dp[j][i-1])
            
print(max(max(dp)))

3. Reference

https://ko.wikipedia.org/wiki/%EC%B5%9C%EC%9E%A5_%EA%B3%B5%ED%86%B5_%EB%B6%80%EB%B6%84_%EC%88%98%EC%97%B4