refactor 91

fishercoder1534 · fishercoder1534 · commit 43151ceec89c · 2018-03-02T15:52:40.000-08:00
diff --git a/src/main/java/com/fishercoder/solutions/_91.java b/src/main/java/com/fishercoder/solutions/_91.java
@@ -1,9 +1,8 @@
 package com.fishercoder.solutions;
 
-import java.util.HashSet;
-import java.util.Set;
-
 /**
+ * 91. Decode Ways
+ *
  * A message containing letters from A-Z is being encoded to numbers using the following mapping:
 
  'A' -> 1
@@ -26,93 +25,25 @@ public class _91 {
      * I then check one digit and two digit combination and save the results along the way.
      * In the end, dp[n] will be the end result.*/
 
-    public static int numDecodings_solution2(String s) {
+    public static class Solution1 {
+      public int numDecodings(String s) {
         if (s == null || s.length() == 0) {
-            return 0;
+          return 0;
         }
         int[] dp = new int[s.length() + 1];
         dp[0] = 1;
         dp[1] = (s.charAt(0) != '0') ? 1 : 0;
         for (int i = 2; i <= s.length(); i++) {
-            int first = Integer.valueOf(s.substring(i - 1, i));
-            int second = Integer.valueOf(s.substring(i - 2, i));
-            if (first > 0 && first <= 9) {
-                dp[i] += dp[i - 1];
-            }
-            if (second >= 10 && second <= 26) {
-                dp[i] += dp[i - 2];
-            }
+          int first = Integer.valueOf(s.substring(i - 1, i));
+          int second = Integer.valueOf(s.substring(i - 2, i));
+          if (first > 0 && first <= 9) {
+            dp[i] += dp[i - 1];
+          }
+          if (second >= 10 && second <= 26) {
+            dp[i] += dp[i - 2];
+          }
         }
         return dp[s.length()];
-    }
-
-    public static void main(String... args) {
-        String msg = "100";
-    }
-
-    /**
-     * My original accepted yet lengthy solution.
-     */
-    public static int numDecodings_solution1(String s) {
-
-        if (s == null || s.length() == 0) {
-            return 0;
-        }
-        Set<String> validStrings = new HashSet();
-        validStrings.add("1");
-        validStrings.add("2");
-        validStrings.add("3");
-        validStrings.add("4");
-        validStrings.add("5");
-        validStrings.add("6");
-        validStrings.add("7");
-        validStrings.add("8");
-        validStrings.add("9");
-        validStrings.add("10");
-        validStrings.add("11");
-        validStrings.add("12");
-        validStrings.add("13");
-        validStrings.add("14");
-        validStrings.add("15");
-        validStrings.add("16");
-        validStrings.add("17");
-        validStrings.add("18");
-        validStrings.add("19");
-        validStrings.add("20");
-        validStrings.add("21");
-        validStrings.add("22");
-        validStrings.add("23");
-        validStrings.add("24");
-        validStrings.add("25");
-        validStrings.add("26");
-
-        int n = s.length();
-        int[] dp = new int[n];
-        if (validStrings.contains(s.substring(0, 1))) {
-            dp[0] = 1;
-        } else {
-            dp[0] = 0;
-        }
-
-        for (int i = 1; i < n; i++) {
-            if (validStrings.contains(s.substring(i, i + 1)) && validStrings.contains(s.substring(i - 1, i + 1))) {
-                if (i > 1) {
-                    dp[i] = dp[i - 2] + dp[i - 1];
-                } else {
-                    dp[1] = 2;
-                }
-            } else if (!validStrings.contains(s.substring(i, i + 1)) && !validStrings.contains(s.substring(i - 1, i + 1))) {
-                return 0;
-            } else if (!validStrings.contains(s.substring(i, i + 1)) && validStrings.contains(s.substring(i - 1, i + 1))) {
-                if (i > 1) {
-                    dp[i] = dp[i - 2];
-                } else {
-                    dp[i] = dp[i - 1];
-                }
-            } else {
-                dp[i] = dp[i - 1];
-            }
-        }
-        return dp[n - 1];
+      }
     }
 }
