题目：

字符串有三种编辑操作:插入一个英文字符、删除一个英文字符或者替换一个英文字符。 给定两个字符串，编写一个函数判定它们是否只需要一次(或者零次)编辑。

示例 1:

输入:

first = "pale"

second = "ple"

输出: True

示例 2:

输入:

first = "pales"

second = "pal"

输出: False

代码实现：

class Solution {
    public boolean oneEditAway(String first, String second) {
        int m = first.length(), n = second.length();
        if (n - m == 1) {
            return oneInsert(first, second);
        } else if (m - n == 1) {
            return oneInsert(second, first);
        } else if (m == n) {
            boolean foundDifference = false;
            for (int i = 0; i < m; i++) {
                if (first.charAt(i) != second.charAt(i)) {
                    if (!foundDifference) {
                        foundDifference = true;
                    } else {
                        return false;
                    }
                }
            }
            return true;
        } else {
            return false;
        }
    }

    public boolean oneInsert(String shorter, String longer) {
        int length1 = shorter.length(), length2 = longer.length();
        int index1 = 0, index2 = 0;
        while (index1 < length1 && index2 < length2) {
            if (shorter.charAt(index1) == longer.charAt(index2)) {
                index1++;
            }
            index2++;
            if (index2 - index1 > 1) {
                return false;
            }
        }
        return true;
    }
}