题目：

题解：

class Solution {public String nearestPalindromic(String n) {long selfNumber = Long.parseLong(n), ans = -1;List<Long> candidates = getCandidates(n);for (long candidate : candidates) {if (candidate != selfNumber) {if (ans == -1 ||Math.abs(candidate - selfNumber) < Math.abs(ans - selfNumber) ||Math.abs(candidate - selfNumber) == Math.abs(ans - selfNumber) && candidate < ans) {ans = candidate;}}}return Long.toString(ans);}public List<Long> getCandidates(String n) {int len = n.length();List<Long> candidates = new ArrayList<Long>() {{add((long) Math.pow(10, len - 1) - 1);add((long) Math.pow(10, len) + 1);}};long selfPrefix = Long.parseLong(n.substring(0, (len + 1) / 2));for (long i = selfPrefix - 1; i <= selfPrefix + 1; i++) {StringBuffer sb = new StringBuffer();String prefix = String.valueOf(i);sb.append(prefix);StringBuffer suffix = new StringBuffer(prefix).reverse();sb.append(suffix.substring(len & 1));String candidate = sb.toString();try {candidates.add(Long.parseLong(candidate));} catch (NumberFormatException ex) {continue;}}return candidates;}
}