longest-common-subsequence solution

Author: hyeri0903

longest-common-subsequence/hyeri0903.java

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+class Solution {
+    public int longestCommonSubsequence(String text1, String text2) {
+        /**
+        1.문제: 가장 긴 common subsequence length return, 없으면 0 return
+        2.constraints
+        - length min = 1, max = 1000
+        - text1, text2 모두 lowercase로 구성
+        3.풀이
+        - dp[i][j] = text1의 앞 i개, text2의 앞 j개를 비교했을 때 LCS 길이
+        - 문자가 같으면: dp[i][j] = dp[i-1][j-1] + 1
+        - 문자가 다르면: dp[i][j] = max(dp[i-1][j], dp[i][j-1]) 
+         */
+        int t1Size = text1.length(); //row
+        int t2Size = text2.length(); //col
+        int[][] dp = new int[t1Size + 1][t2Size + 1];
+
+        for(int i = 1; i <= t1Size; i++) {
+            for(int j = 1; j <= t2Size; j++) {
+                if(text1.charAt(i-1) == text2.charAt(j-1)) {
+                    dp[i][j] = dp[i-1][j-1] + 1;
+                } else {
+                    dp[i][j] = Math.max(dp[i-1][j], dp[i][j-1]);
+                }
+            }
+        }
+        return dp[t1Size][t2Size];
+    }
+}