public String nearestPalindromic(String n) {
// 处理特殊值 1位数
if (n.length() == 1) {
return String.valueOf(Math.abs(Long.parseLong(n) - 1));
}
// 原始数据
Long num = Long.parseLong(n);
// 原始数据直接 转回文
Long huiwen = Long.parseLong(huiwen(n));
// 从中间点数字 +1 再转回文 比如 9999 -> 10099 -> 10001
Long huiwenAdd1 = Long.parseLong(midAdd1(n));
// 从中间点数字 -1 再转回文 比如 10001 -> 9901 -> 9999
Long huiwenMin1 = Long.parseLong(midMin1(n));
// 找寻差值最小的数字
Long res = 0L;
Long abs = Long.MAX_VALUE;
if (!huiwen.equals(num)) {
res = huiwen;
abs = Math.abs(huiwen - num);
}
long add1Abs = huiwenAdd1 - num;
if (add1Abs < abs) {
abs = add1Abs;
res = huiwenAdd1;
}
long min1Abs = num - huiwenMin1;
if (min1Abs <= abs) {
abs = min1Abs;
res = huiwenMin1;
}
return res.toString();
}
public String midAdd1(String n) {
char[] chars = n.toCharArray();
int mid = chars.length % 2 == 0 ? chars.length / 2 - 1 : chars.length / 2;
for (int i = mid; i > -1; i--) {
if (chars[i] == '9') {
chars[i] = '0';
} else {
chars[i] += 1;
break;
}
}
if (chars[0] == '0') {
char[] newChars = new char[chars.length + 1];
newChars[0] = '1';
System.arraycopy(chars, 0, newChars, 1, chars.length);
return huiwen(new String(newChars));
} else {
return huiwen(new String(chars));
}
}
public String midMin1(String n) {
char[] chars = n.toCharArray();
int mid = chars.length % 2 == 0 ? chars.length / 2 - 1 : chars.length / 2;
for (int i = mid; i > -1; i--) {
if (chars[i] == '0') {
chars[i] = '9';
} else {
chars[i] -= 1;
break;
}
}
if (chars[0] == '0') {
char[] newChars = new char[chars.length - 1];
newChars[0] = '9';
System.arraycopy(chars, 1, newChars, 1, chars.length - 2);
return huiwen(new String(newChars));
} else {
return huiwen(new String(chars));
}
}
public String huiwen(String n) {
char[] chars = n.toCharArray();
int mid = chars.length / 2;
for (int i = 0; i < mid; i++) {
chars[chars.length - 1 - i] = chars[i];
}
return new String(chars);
}
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原文链接：https://blog.csdn.net/zhangdx001/article/details/105938049/
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