add kotlin/java solution for 402 Remove-K-Digits

MagicienDeCode · MagicienDeCode · commit 32373ffbb31e · 2020-05-13T15:13:05.000+02:00
diff --git a/May-LeetCoding-Challenge/13-Remove-K-Digits/Remove-K-Digits.java b/May-LeetCoding-Challenge/13-Remove-K-Digits/Remove-K-Digits.java
@@ -0,0 +1,60 @@
+import java.util.Stack;
+
+public class RemoveKDigits402 {
+    public String removeKdigits(final String num, final int k) {
+        if (num.length() == k) {
+            return "0";
+        }
+        int currentK = k;
+        Stack<Character> characterStack = new Stack<>();
+        for (int index = 0; index < num.length(); index++) {
+            final Character c = num.charAt(index);
+            while (currentK > 0 && !characterStack.empty() && characterStack.peek() > c) {
+                characterStack.pop();
+                --currentK;
+            }
+            characterStack.push(c);
+        }
+        while (currentK > 0) {
+            characterStack.pop();
+            --currentK;
+        }
+        final StringBuilder result = new StringBuilder();
+        while (!characterStack.isEmpty()) {
+            result.append(characterStack.pop());
+        }
+        result.reverse();
+        if (result.length() == 1) {
+            return result.toString();
+        }
+        while (result.length() > 1 && result.charAt(0) == '0') {
+            result.deleteCharAt(0);
+        }
+        return result.toString();
+    }
+    /*
+    public String removeKdigits(String num, int k) {
+        if (num.length() == k) {
+            return "0";
+        }
+        final StringBuilder result = new StringBuilder(num);
+
+        for (int time = 1; time <= k; time++) {
+            int index = 0;
+            while (index < result.length() - 1 &&
+            result.charAt(index) <= result.charAt(index + 1)) {
+                ++index;
+            }
+            result.deleteCharAt(index);
+        }
+
+        if (result.length() == 1) {
+            return result.toString();
+        }
+        while (result.length() > 1 && result.charAt(0) == '0') {
+            result.deleteCharAt(0);
+        }
+        return result.toString();
+    }
+     */
+}
diff --git a/May-LeetCoding-Challenge/13-Remove-K-Digits/Remove-K-Digits.kt b/May-LeetCoding-Challenge/13-Remove-K-Digits/Remove-K-Digits.kt
@@ -0,0 +1,99 @@
+import java.util.*
+
+class RemoveKDigitsKotlin402 {
+    fun removeKdigits(num: String, k: Int): String {
+        if (num.length == k) {
+            return "0"
+        }
+        val charStack: Stack<Char> = Stack()
+        var currentK = k
+        num.forEach {
+            while (currentK > 0 && charStack.isNotEmpty() && charStack.peek() > it) {
+                charStack.pop()
+                --currentK
+            }
+            charStack.push(it)
+        }
+        while (currentK > 0) {
+            charStack.pop()
+            --currentK
+        }
+        val result = StringBuilder()
+        while (charStack.isNotEmpty()) {
+            result.append(charStack.pop())
+        }
+        result.reverse()
+        return when (result.length) {
+            1 -> result.toString()
+            else -> {
+                while (result.length > 1 && result[0] == '0') {
+                    result.deleteCharAt(0)
+                }
+                result.toString()
+            }
+        }
+    }
+    /*
+    fun removeKdigits(num: String, k: Int): String {
+        if (num.length == k) {
+            return "0"
+        }
+        val result = StringBuilder(num)
+        for (i in 1..k) {
+            var index = 0
+            while (index < result.length - 1 && result[index] <= result[index + 1]) {
+                index++
+            }
+            result.deleteCharAt(index)
+        }
+        return when (result.length) {
+            1 -> result.toString()
+            else -> {
+                while (result.length > 1 && result[0] == '0') {
+                    result.deleteCharAt(0)
+                }
+                result.toString()
+            }
+        }
+    }
+     */
+    /*
+    !! wrong !!
+    private fun recursion(
+        num: String,
+        result: IntArray,
+        start: Int,
+        stringBuilder: StringBuilder,
+        remain: Int
+    ) {
+        if (remain == 0) {
+            val currentInt = stringBuilder.toString().toInt()
+            if (currentInt < result[0]) {
+                result[0] = currentInt
+            }
+        } else {
+            for (index in start until num.length) {
+                recursion(num, result, index + 1, stringBuilder.append(num[index]), remain - 1)
+                stringBuilder.deleteCharAt(stringBuilder.length - 1)
+            }
+        }
+    }
+     */
+    /*
+    !! wrong !!
+    private fun getIntAfterRemoveRange(nums: String, start: Int, end: Int): Int {
+        val resultString = "${nums.substring(0, start)}${nums.substring(end, nums.length)}"
+        return when {
+            resultString.isEmpty() -> 0
+            else -> resultString.toInt()
+        }
+     */
+}
+
+fun main() {
+    val solution = RemoveKDigitsKotlin402()
+    println(solution.removeKdigits("5337", 2)) // 33
+    println(solution.removeKdigits("1432219", 3)) // 1219
+    println(solution.removeKdigits("53037", 4)) // 0
+    println(solution.removeKdigits("530137", 4)) // 0
+}
