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55 lines
1.2 KiB
55 lines
1.2 KiB
package class28;
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public class Code02_AddShortestEnd {
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public static String shortestEnd(String s) {
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if (s == null || s.length() == 0) {
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return null;
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}
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char[] str = manacherString(s);
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int[] pArr = new int[str.length];
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int C = -1;
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int R = -1;
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int maxContainsEnd = -1;
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for (int i = 0; i != str.length; i++) {
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pArr[i] = R > i ? Math.min(pArr[2 * C - i], R - i) : 1;
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while (i + pArr[i] < str.length && i - pArr[i] > -1) {
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if (str[i + pArr[i]] == str[i - pArr[i]])
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pArr[i]++;
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else {
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break;
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}
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}
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if (i + pArr[i] > R) {
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R = i + pArr[i];
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C = i;
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}
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if (R == str.length) {
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maxContainsEnd = pArr[i];
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break;
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}
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}
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char[] res = new char[s.length() - maxContainsEnd + 1];
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for (int i = 0; i < res.length; i++) {
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res[res.length - 1 - i] = str[i * 2 + 1];
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}
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return String.valueOf(res);
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}
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public static char[] manacherString(String str) {
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char[] charArr = str.toCharArray();
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char[] res = new char[str.length() * 2 + 1];
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int index = 0;
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for (int i = 0; i != res.length; i++) {
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res[i] = (i & 1) == 0 ? '#' : charArr[index++];
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}
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return res;
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}
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public static void main(String[] args) {
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String str1 = "abcd123321";
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System.out.println(shortestEnd(str1));
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}
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}
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