Leetcode•May 02, 2026
Remove K Digits
Hazrat Ali
Leetcode
Given string num representing a non-negative integer num, and an integer k, return the smallest possible integer after removing k digits from num.
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.
Solution
var removeKdigits = function(num, k) {
let stack = [];
for (let digit of num) {
while (stack.length && k > 0 && stack[stack.length - 1] > digit) {
stack.pop();
k--;
}
stack.push(digit);
}
while (k > 0) {
stack.pop();
k--;
}
let result = stack.join('').replace(/^0+/, '');
return result === '' ? '0' : result;
};