# LeetCode – Remove K Digits (Java)

Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible.

Note:

The length of num is less than 10002 and will be ≥ k.

The given num does not contain any leading zero.

Example 1:

Input: num = "1432219", k = 3 Output: "1219" Explanation: Remove the three digits 4, 3, and 2 to form the new number 1219 which is the smallest.

Example 2:

Input: num = "10200", k = 1 Output: "200" Explanation: Remove the leading 1 and the number is 200. Note that the output must not contain leading zeroes.

Example 3:

Input: num = "10", k = 2 Output: "0" Explanation: Remove all the digits from the number and it is left with nothing which is 0.

**Java Solution**

public String removeKdigits(String num, int k) { if(num.length()==k) return "0"; StringBuilder sb = new StringBuilder(num); for(int j=0; j<k; j++){ int i=0; while(i<sb.length()-1&&sb.charAt(i)<=sb.charAt(i+1)){ i++; } sb.delete(i, i+1); } //remove leading 0's while (sb.length() > 1 && sb.charAt(0)=='0') sb.delete(0,1); if(sb.length()==0){ return "0"; } return sb.toString(); } |

<pre><code> String foo = "bar"; </code></pre>