Merge pull request #2652 from ColstonBod-oy/patch-11

Update 1143-longest-common-subsequence.java

Author: sujal-goswami

Diff for: java/1143-longest-common-subsequence.java

@@ -22,33 +22,20 @@ public int LCS(String s1, String s2, int i, int j, int[][] dp) {
 
 // Iterative version
 class Solution {
-
+    
     public int longestCommonSubsequence(String text1, String text2) {
-        //O(n*m)/O(n*m)  time/memory
-        if (text1.isEmpty() || text2.isEmpty()) {
-            return 0;
-        }
-
-        int[][] dp = new int[text1.length() + 1][text2.length() + 1];
-
-        for (int i = 0; i <= text1.length(); i++) {
-            dp[i][0] = 0;
-        }
-
-        for (int j = 0; j <= text2.length(); j++) {
-            dp[0][j] = 0;
-        }
+        int[][] dp = new int[text1.length() + 1][text2.length() + 1];    
 
-        for (int i = 1; i <= text1.length(); i++) {
-            for (int j = 1; j <= text2.length(); j++) {
-                if (text1.charAt(i - 1) == text2.charAt(j - 1)) {
-                    dp[i][j] = 1 + dp[i - 1][j - 1];
+        for (int i = text1.length() - 1; i >= 0; i--) {
+            for (int j = text2.length() - 1; j >= 0; j--) {
+                if (text1.charAt(i) == text2.charAt(j)) {
+                    dp[i][j] = 1 + dp[i + 1][j + 1];
                 } else {
-                    dp[i][j] = Math.max(dp[i][j - 1], dp[i - 1][j]);
+                    dp[i][j] = Math.max(dp[i][j + 1], dp[i + 1][j]);
                 }
             }
         }
 
-        return dp[text1.length()][text2.length()];
+        return dp[0][0];
     }
 }