KMP

Author: idf

src/ImplementstrStr/Solution.java

@@ -0,0 +1,75 @@
+package ImplementstrStr;
+
+/**
+ * User: Danyang
+ * Date: 1/29/2015
+ * Time: 19:26
+ *
+ * Implement strStr().
+
+ Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
+ */
+public class Solution {
+    /**
+     * KMP
+     *
+     * Notice:
+     * 1. build a table of the length of matched prefix_suffix - PREFIX SUFFIX LENGTH TABLE
+     * 2. test case "mississippi", "issip"; "redoredoreo", "redoreo"
+     * 3. S[i+j]
+     * @param haystack
+     * @param needle
+     * @return
+     */
+    public int strStr(String haystack, String needle) {
+        if(haystack.length()<needle.length())
+            return -1;
+        if(needle.length()<=1)
+            return haystack.indexOf(needle);
+
+        char[] S = haystack.toCharArray();
+        char[] W = needle.toCharArray();
+        // build prefix_suffix_length_table
+        int[] T = new int[W.length+1];
+        T[0] = -1;
+        T[1] = 0;
+        int i = 0;
+        int j;
+        for(j=1; j<W.length; ) {
+            if(W[i]==W[j]) {
+                T[j+1] = i+1;
+                i++;
+                j++;
+            }
+            else if(i!=0) {  // reredo...rerereply
+                i = T[i];
+            }
+            else {
+                T[j+1] = 0;
+                j++;
+            }
+        }
+
+        // search
+        i = 0;
+        j = 0;
+        while(i+j<S.length) {
+            if(S[i+j]==W[j]) {
+                j++;
+                if(j==W.length)
+                    return i;
+            }
+            else {
+                if(T[j]!=-1) {
+                    i = i+j-T[j];
+                    j = T[j];
+                }
+                else {
+                    i += 1;
+                    j = 0;
+                }
+            }
+        }
+        return -1;
+    }
+}

src/SubstringwithConcatenationofAllWords/Solution.java

@@ -57,7 +57,6 @@ public List<Integer> findSubstring(String S, String[] L) {
                     workingWin.clear();
                     win_e = -1;
                     Lmap = new HashMap<>(Lmap_origin);
-                    continue;
                 }
             }