[BOJ]#9251. LCS/골드5/힌트

https://www.acmicpc.net/problem/9251

Author: zaqquum

Hongjoo/백준/lcs.py

@@ -0,0 +1,31 @@
+"""
+[BOJ]#9251.LCS / DP /Gold5/ 2025.09.09
+https://www.acmicpc.net/problem/9251
+#####
+
+"""
+import sys
+input = sys.stdin.readline
+# 1. 입력 변수 - a 문자열 / b문자열
+a = list(input())[:-1]
+b= list(input())[:-1]
+# LCS 행렬 0 초기화
+lcs = [[0]*(len(b)+1) for _ in range(len(a)+1)]
+
+#2. LCS (Longest Common Subsequence) 점화식
+"""
+i. a[i] VS b[j] 문자 비교하기
+  (1) SAME(=) -> dp[i][j] = 위쪽 대각선 +1 
+  (2) DIFF(!=) -> dp[i][j] = MAX(왼쪽 , 위쪽)
+
+ii. 최종 LCS = dp[-1][-1]
+"""
+for i in range(1,len(a)+1) :
+  for j in range(1, len(b)+1) :
+    if a[i-1] == b[j-1]:
+      lcs[i][j] = lcs[i-1][j-1] + 1
+    else :
+      lcs[i][j] = max(lcs[i-1][j] , lcs[i][j-1])
+
+# print(lcs)
+print(lcs[-1][-1])