UVA 11888 - Abnormal 89's(Manachar)

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UVA 11888 - Abnormal 89's

题目链接

题意：给定一个字符串，判断类型，一共三种，两个回文拼接成的，一个回文，其它

思路：利用Manachar处理出每个位置的最长回文，然后扫描一遍去判断即可

代码：

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N = 200005;int t, p[N * 2], n, len;char str[N], s[N * 2];void manachar() {    len = 2;    s[0] = '@'; s[1] = '#';    for (int i = 0; i < n; i++) {s[len++] = str[i];s[len++] = '#';    }    s[len] = '\0';    int mx = 0, id;    for (int i = 1; i < len; i++) {if (mx > i) p[i] = min(p[2 * id - i], mx - i);else p[i] = 1;while (s[i + p[i]] == s[i - p[i]]) p[i]++;if (i + p[i] > mx) {    id = i;    mx = i + p[i];}    }}int judge() {    int need = 0;    for (int i = 2; i < len - 1; i++) {if ((p[i] - 1) / 2 == need) {    int l = i + p[i] - 1;    int r = len - 1;    int mid = (l + r) / 2;    int lneed = need * 2;    if (s[i] != '#') lneed++;    int rneed = n - lneed;    if (rneed && rneed == p[mid] - 1) return 0;}if (s[i] != '#') need++;    }    if (p[len / 2] - 1 == n) return 1;    return 2;}int main() {    scanf("%d", &t);    while (t--) {scanf("%s", str);n = strlen(str);manachar();if (judge() == 0) printf("alindrome\n");else if (judge() == 1) printf("palindrome\n");else printf("simple\n");    }    return 0;}

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