hdu 1867 A + B for you again

        hdu 1867 A + B for you again

        題目沒有說明輸入一定是前一個字符串的後綴和後一個字符串匹配，所以需要進行兩次kmp匹配，然後得出最大的匹配數。

#include <stdio.h>
#include <string.h>

#define MAX 100005

char strA[MAX], strB[MAX];
int next[MAX];

void getNext(char* str, int* next) {
	int len;
	int j, k;
	
	j = 0;
	k = -1;
	next[0] = k;
	len = strlen(str) - 1;
	
	while (j < len) {
		if (k == -1 || str[k] == str[j]) {
			++k, ++j;
			
			if (str[k] == str[j]) {
				next[j] = next[k];
			} else {
				next[j] = k;
			}
		} else {
			k = next[k];
		}
	}
}

int kmp(char* strA, char* strB) {
	int lenA, lenB;
	int i, j;
	
	i = j = 0;
	lenA = strlen(strA);
	lenB = strlen(strB);
	getNext(strB, next);
	
	if (lenA > lenB) {
		i = lenA - lenB;
	}
	
	while (i < lenA) {
		if (j == -1 || strA[i] == strB[j]) {
			++j, ++i;
		} else {
			j = next[j];
		}
	}
	
	return j;
}

int main() {
	int numA, numB, num;
	int lenA, lenB, len;
	int i;

	while (scanf("%s%s", strA, strB) != EOF) {
		numA = kmp(strA, strB);
		numB = kmp(strB, strA);
		num = numA > numB ? numA : numB;

		if (num == 0) {
			if (strcmp(strA, strB) < 0) {
				printf("%s%s\n", strA, strB);
			} else {
				printf("%s%s\n", strB, strA);
			}
		} else {
			if (numA == num) {
				printf("%s%s", strA, strB + num);
			} else {
				printf("%s%s", strB, strA + num);
			}

			printf("\n");
		}
	}

	return 0;
}