Create Solution.java

Author: Jerring

solution/0402.Remove K Digits/Solution.java

@@ -0,0 +1,25 @@
+class Solution {
+    public String removeKdigits(String num, int k) {
+        if (k <= 0) {
+            return num;
+        }
+        if (num.length() <= k) {
+            return "0";
+        }
+        int len = num.length() - k;
+        char[] cs = new char[num.length()];
+        int top = -1;
+        for (char c : num.toCharArray()) {
+            while (top >= 0 && cs[top] > c && k > 0) {
+                --top;
+                --k;
+            }
+            cs[++top] = c;
+        }
+        int offset = 0;
+        while (offset <= top && cs[offset] == '0') {
+            ++offset;
+        }
+        return offset > top ? "0" : new String(cs, offset, len - offset);
+    }
+}