llint

Author: piggy1991

lintcode/dp/LongestCommonSubstring.java

@@ -0,0 +1,41 @@
+package Algorithms.lintcode.dp;
+
+public class LongestCommonSubstring {
+    /**
+     * @param A, B: Two string.
+     * @return: the length of the longest common substring.
+     */
+    public int longestCommonSubstring(String A, String B) {
+        // write your code here
+        if (A == null || B == null) {
+            return 0;
+        }
+        
+        int lenA = A.length();
+        int lenB = B.length();
+        
+        // bug 1: use error init.
+        int[][] D = new int[lenA + 1][lenB + 1];
+        
+        int max = 0;
+        
+        // BUG 2: should use <= instead of <
+        for (int i = 0; i <= lenA; i++) {
+            for (int j = 0; j <= lenB; j++) {
+                if (i == 0 || j == 0) {
+                    D[i][j] = 0;
+                } else {
+                    if (A.charAt(i - 1) == B.charAt(j - 1)) {
+                        D[i][j] = D[i - 1][j - 1] + 1;
+                    } else {
+                        D[i][j] = 0;
+                    }
+                }
+                
+                max = Math.max(max, D[i][j]);
+            }
+        }
+        
+        return max;
+    }
+}