Create 0767-reorganize-string.kt

Author: a93a

kotlin/0767-reorganize-string.kt

@@ -0,0 +1,76 @@
+class Solution {
+    fun reorganizeString(s: String): String {
+        var count = HashMap<Char, Int>().apply {
+            for (c in s)
+                this[c] = getOrDefault(c, 0) + 1
+        }
+
+        val maxHeap = PriorityQueue<Pair<Int, Char>>() { a, b ->
+            b.first - a.first
+        }
+        
+        for ((ch, cnt) in count)
+            maxHeap.add(cnt to ch)
+
+        var prev: Pair<Int, Char>? = null
+        var res = StringBuilder()
+        while (maxHeap.isNotEmpty() || prev != null) {
+            if (maxHeap.isEmpty() && prev != null)
+                return ""
+
+            var (cnt, ch) = maxHeap.poll()
+            res.append(ch)
+            cnt--
+
+            prev?.let {
+                maxHeap.add(it)
+                prev = null
+            }
+
+            if (cnt != 0)
+                prev = cnt to ch
+        } 
+
+        return res.toString()
+    }
+}
+
+// another solution without heap
+class Solution {
+    fun reorganizeString(s: String): String {
+        val freq = IntArray (26).apply {
+            for (c in s) this[c - 'a']++
+        }
+
+        var maxFreq = -1
+        var maxChar = -1
+        for (letter in 0..25) {
+            if (freq[letter] > maxFreq) {
+                maxFreq = freq[letter]
+                maxChar = letter
+            }
+        }
+
+        if (maxFreq > (s.length + 1) / 2) return ""
+
+        var i = 0
+        val res = CharArray (s.length).apply {        
+            while (freq[maxChar] > 0) {
+                this[i] = 'a' + maxChar
+                i += 2
+                freq[maxChar]--
+            }
+        }
+
+        for (letter in 0..25) {
+            while (freq[letter] > 0) {
+                if (i > s.lastIndex) i = 1
+                res[i] = 'a' + letter
+                i += 2
+                freq[letter]--
+            }      
+        }
+
+        return res.joinToString("")
+    }
+}