add 358

fishercoder1534 · fishercoder1534 · commit bdc28114fe24 · 2017-06-08T09:05:29.000-07:00
diff --git a/README.md b/README.md
@@ -196,6 +196,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |361|[Bomb Enemy](https://leetcode.com/problems/bomb-enemy/)|[Solution](../master/src/main/java/com/fishercoder/solutions/BombEnemies.java)| O(?)|O(?) | Medium| 
 |360|[Sort Transformed Array](https://leetcode.com/problems/sort-transformed-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_360.java)| O(n)|O(1) | Medium| Two Pointers, Math
 |359|[Logger Rate Limiter](https://leetcode.com/problems/logger-rate-limiter/)|[Solution](../master/src/main/java/com/fishercoder/solutions/LoggerRateLimiter.java)| amortized O(1)|O(k) | Easy| HashMap
+|358|[Rearrange String k Distance Apart](https://leetcode.com/problems/rearrange-string-k-distance-apart/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_358.java)| O(n)|O(n) | Hard| HashMap, Heap, Greedy
 |357|[Count Numbers with Unique Digits](https://leetcode.com/problems/count-numbers-with-unique-digits/)|[Solution](../master/src/main/java/com/fishercoder/solutions/CountNumbersWithUniqueDigits.java)| O(?)|O(?) | Medium|
 |356|[Line Reflection](https://leetcode.com/problems/line-reflection/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_356.java)| O(n)|O(n) | Medium| HashSet
 |355|[Design Twitter](https://leetcode.com/problems/design-twitter/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_355.java)| O(n)|O(n) | Medium| Design, HashMap, Heap
diff --git a/src/main/java/com/fishercoder/solutions/_358.java b/src/main/java/com/fishercoder/solutions/_358.java
@@ -0,0 +1,54 @@
+package com.fishercoder.solutions;
+
+import java.util.*;
+
+/**
+ * 358. Rearrange String k Distance Apart
+ *
+ * Given a non-empty string s and an integer k, rearrange the string such that the same characters are at least distance k from each other.
+
+ All input strings are given in lowercase letters. If it is not possible to rearrange the string, return an empty string "".
+ Example 1:
+ s = "aabbcc", k = 3
+ Result: "abcabc"
+ The same letters are at least distance 3 from each other.
+
+ Example 2:
+ s = "aaabc", k = 3
+ Answer: ""
+ It is not possible to rearrange the string.
+
+ Example 3:
+ s = "aaadbbcc", k = 2
+ Answer: "abacabcd"
+ Another possible answer is: "abcabcda"
+ The same letters are at least distance 2 from each other.
+ */
+public class _358 {
+
+    public String rearrangeString(String s, int k) {
+        Map<Character, Integer> count = new HashMap<>();
+        for (char c : s.toCharArray()) {
+            count.put(c, count.getOrDefault(c, 0) + 1);
+        }
+
+        PriorityQueue<Map.Entry<Character, Integer>> heap = new PriorityQueue<>((a, b) -> b.getValue() - a.getValue());
+        heap.addAll(count.entrySet());
+
+        Queue<Map.Entry<Character, Integer>> waitQueue = new LinkedList<>();
+
+        StringBuilder stringBuilder = new StringBuilder();
+        while (!heap.isEmpty()) {
+            Map.Entry<Character, Integer> entry = heap.poll();
+            stringBuilder.append(entry.getKey());
+            entry.setValue(entry.getValue()-1);
+            waitQueue.offer(entry);
+            if (waitQueue.size() < k) continue; //there's only k-1 chars in the waitHeap, not full yet
+            Map.Entry<Character, Integer> front = waitQueue.poll();
+            if (front.getValue() > 0) heap.offer(front);
+        }
+
+        return stringBuilder.length() == s.length() ? stringBuilder.toString() : "";
+    }
+
+}
diff --git a/src/test/java/com/fishercoder/_358Test.java b/src/test/java/com/fishercoder/_358Test.java
@@ -0,0 +1,33 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._358;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+/**
+ * Created by stevesun on 6/8/17.
+ */
+public class _358Test {
+
+    private static _358 test;
+
+    @BeforeClass
+    public static void setup(){
+        test = new _358();
+    }
+
+    @Test
+    public void test1(){
+        System.out.println(test.rearrangeString("aabbcc", 3));
+    }
+
+    @Test
+    public void test2(){
+        System.out.println(test.rearrangeString("aaabc", 3));
+    }
+
+    @Test
+    public void test3(){
+        System.out.println(test.rearrangeString("aaadbbcc", 2));
+    }
+}
