minStickers

src/leo/class19/StickersToSpellWord.java

@@ -56,11 +56,11 @@ public class StickersToSpellWord {
             char[] s = sticker.toCharArray();
             char[] t = target.toCharArray();
             int[] count = new int[26];
-            for (int i = 0; i < s.length; i++) {
-                count[s[i] - 'a']++;
-            }
             for (int i = 0; i < t.length; i++) {
-                count[t[i] - 'a']--;
+                count[t[i] - 'a']++;
+            }
+            for (int i = 0; i < s.length; i++) {
+                count[s[i] - 'a']--;
             }
             StringBuffer sb = new StringBuffer();
             for (int i = 0; i < count.length; i++) {
@@ -74,6 +74,54 @@ public class StickersToSpellWord {
         }
     }
 
+    static class Recursion1 {
+        public static int minStickers(String[] stickers, String target) {
+            if (target == null || target.length() == 0 || stickers == null || stickers.length == 0) {
+                return -1;
+            }
+            int ans = process(stickers, target);
+            return ans == Integer.MAX_VALUE ? -1 : ans;
+        }
+
+        private static int process(String[] stickers, String target) {
+            if (target.length() == 0) {
+                return 0;
+            }
+            int min = Integer.MAX_VALUE;
+            for (String sticker : stickers) {
+                String rest = minus(sticker, target);
+                if (rest.length() != target.length()) {
+                    min = Math.min(min, process(stickers, rest));
+                }
+            }
+            return min + (min == Integer.MAX_VALUE ? 0 : 1);
+        }
+
+        private static String minus(String sticker, String target) {
+            int[] count = new int[26];
+            char[] sChar = sticker.toCharArray();
+            char[] tChar = target.toCharArray();
+            for (int i = 0; i < tChar.length; i++) {
+                count[tChar[i] - 'a']++;
+            }
+            for (int i = 0; i < sChar.length; i++) {
+                count[sChar[i] - 'a']--;
+            }
+            StringBuffer sb = new StringBuffer();
+            for (int i = 0; i < 26; i++) {
+                if (count[i] > 0) {
+                    for (int j = 0; j < count[i]; j++) {
+                        sb.append((char) (i + 'a'));
+                    }
+                }
+            }
+            return sb.toString();
+        }
+
+    }
+
+
+
     static class DpZuo {
         public static int minStickers(String[] stickers, String target) {
             int N = stickers.length;
@@ -235,12 +283,70 @@ public class StickersToSpellWord {
         }
     }
 
+    static class Dp2 {
+        public static int minStickers(String[] stickers, String target) {
+            if (target == null || target.length() == 0) {
+                return -1;
+            }
+            int n = stickers.length;
+            int[][] sCount = new int[n][26];
+            for (int i = 0; i < n; i++) {
+                char[] chars = stickers[i].toCharArray();
+                for (char c : chars) {
+                    sCount[i][c - 'a']++;
+                }
+            }
+            Map<String, Integer> dp = new HashMap<>();
+            dp.put("", 0);
+            int ans = process(sCount, target, dp);
+            return ans == Integer.MAX_VALUE ? -1 : ans;
+        }
+
+        private static int process(int[][] stickers, String target, Map<String, Integer> dp) {
+            if (dp.containsKey(target)) {
+                return dp.get(target);
+            }
+            if (target.length() == 0) {
+                return 0;
+            }
+            int[] tCount = new int[26];
+            char[] t = target.toCharArray();
+            for (char c : t) {
+                tCount[c - 'a']++;
+            }
+            int min = Integer.MAX_VALUE;
+            for (int i = 0; i < stickers.length; i++) {
+                int[] sticker = stickers[i];
+                //从target第一个字符开始,剪枝
+                if (sticker[t[0] - 'a'] > 0) {
+                    StringBuffer sb = new StringBuffer();
+                    for (int j = 0; j < 26; j++) {
+                        int mun = tCount[j] - sticker[j];
+                        for (int k = 0; k < mun; k++) {
+                            sb.append((char) (j + 'a'));
+                        }
+                    }
+                    String rest = sb.toString();
+                    min = Math.min(min, process(stickers, rest, dp));
+                }
+            }
+            min += (min == Integer.MAX_VALUE ? 0 : 1);
+            dp.put(target, min);
+            return min;
+        }
+
+    }
+
     public static void main(String[] args){
 
         String[] stickers = {"heavy", "claim", "seven", "set", "had", "it", "dead", "jump", "design", "question", "sugar", "dress", "any", "special", "ground", "huge", "use", "busy", "prove", "there", "lone", "window", "trip", "also", "hot", "choose", "tie", "several", "be", "that", "corn", "after", "excite", "insect", "cat", "cook", "glad", "like", "wont", "gray", "especially", "level", "when", "cover", "ocean", "try", "clean", "property", "root", "wing"};
         String target = "travelbell";
-        System.out.println(Dp.minStickers(stickers, target));
+        /*String[] stickers = {"heavy", "claim", "seven", "set", "had", "it", "dead", "sugar"};
+        String target = "travelell";*/
+        /*System.out.println(Recursion1.minStickers(stickers, target));
+        System.out.println(Recursion.minStickers(stickers, target));*/
         System.out.println(Dp1.minStickers(stickers, target));
+        System.out.println(Dp2.minStickers(stickers, target));
 
     }
 }