BZOJ 1355: [Baltic2009]Radio Transmission( kmp )

自己YY一下可以发现answer = n - fail[ n ]

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#include<cstdio>#include<cstring>#include<algorithm>#include<iostream> #define rep( i , n ) for( int i = 0 ; i < n ; i++ )#define clr( x , c ) memset( x , c , sizeof( x ) )#define Rep( i , n ) for( int i = 1 ; i < n ; ++i ) using namespace std; const int maxn = int( 1e6 ) + 5; char S[ maxn ];int fail[ maxn ];int len;void build_fail() { fail[ 0 ] = fail[ 1 ] = 0; Rep( i , len ) { int t = fail[ i ]; while( t && S[ t ] != S[ i ] ) t = fail[ t ]; fail[ i + 1 ] = S[ t ] == S[ i ] ? t + 1 : 0; } } void Read() { cin >> len; rep( i , len ) { char c = getchar(); while ( ! islower( c ) ) c = getchar(); S[ i ] = c; } }int main() {// freopen( "test.in" , "r" , stdin ); Read(); build_fail(); cout << len - fail[ len ] << "\n"; return 0;}

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1355: [Baltic2009]Radio Transmission

Time Limit: 10 Sec Memory Limit: 64 MB
Submit: 419 Solved: 276
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Description

给你一个字符串，它是由某个字符串不断自我连接形成的。 但是这个字符串是不确定的，现在只想知道它的最短长度是多少.

Input

第一行给出字符串的长度,1 < L ≤ 1,000,000. 第二行给出一个字符串，全由小写字母组成.

Output

输出最短的长度

Sample Input

8
cabcabca

Sample Output

3

HINT

对于样例,我们可以利用"abc"不断自我连接得到"abcabcabc",读入的cabcabca,是它的子串

Source