【LeetCode】 68 移掉K位数字

题目：

DJI 8.16第三题

解题思路：

贪心算法

https://leetcode-cn.com/problems/remove-k-digits/solution/yi-diao-kwei-shu-zi-by-leetcode/

代码：

package com.janeroad;

import java.util.LinkedList;

/**
 * Created on 2020/8/16.
 *
 * [@author](https://my.oschina.net/arthor) LJN
 */
public class Test28 {

    public static void main(String[] args)  {
        System.out.println(removeKdigits("71245323308", 4));
    }


    public static String removeKdigits(String num, int k) {
        LinkedList<Character> stack = new LinkedList<Character>();

        for(char digit : num.toCharArray()) {
            while(stack.size() > 0 && k > 0 && stack.peekLast() > digit) {
                stack.removeLast();
                k -= 1;
            }
            stack.addLast(digit);
        }

        /* remove the remaining digits from the tail. */
        for(int i=0; i<k; ++i) {
            stack.removeLast();
        }

        // build the final string, while removing the leading zeros.
        StringBuilder ret = new StringBuilder();
        boolean leadingZero = true;
        for(char digit: stack) {
            if(leadingZero && digit == '0') continue;
            leadingZero = false;
            ret.append(digit);
        }

        /* return the final string  */
        if (ret.length() == 0) return "0";
        return ret.toString();
    }

}

来源：oschina

链接：https://my.oschina.net/u/4248053/blog/4498017