【CodeForces】471D MUH and Cube Walls KMP

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传送门：【CodeForces】471D MUH and Cube Walls

题目分析：很容易想到KMP，然后可以进一步的想到如果轮廓能匹配，也就意味着相邻两个匹配的主串减模式串的值相同即可匹配。

代码如下：

#include <cstdio>#include <cstring>#include <algorithm> #define rep( i , a , b ) for ( int i = ( a ) ;i <  ( b ) ;++ i )#define rev( i , a , b ) for ( int i = ( a ) ;i >= ( b ) ;-- i )#define For( i , a , b ) for ( int i = ( a ) ;i <= ( b ) ;++ i )#define clr( a , x ) memset ( a , x , sizeof a ) typedef long long LL ; const int MAXN = 200005 ;int s[MAXN] ;int p[MAXN] ;int next[MAXN] ;int n , m ;int cmp ( int i , int j , int a[] , int b[] ) {if ( j == 1 ) return 1 ;return a[i] - b[j] == a[i - 1] - b[j - 1] ;}void get_next () {next[1] = 0 ;int j = 0 ;For ( i , 2 , m ) {while ( j && !cmp ( i , j + 1 , p , p ) ) j = next[j] ;if ( cmp ( i , j + 1 , p , p ) ) ++ j ;next[i] = j ;}}void get_kmp () {int ans = 0 ;int j = 0 ;For ( i , 1 , n ) {while ( j && !cmp ( i , j + 1 , s , p ) ) j = next[j] ;if ( cmp ( i , j + 1 , s , p ) ) {++ j ;if ( j == m ) {++ ans ;//printf ( "%d\n" , i ) ;j = next[j] ;}} else j = next[j] ;//printf ( "%d\n" , j ) ;}printf ( "%d\n" , ans ) ;}void solve () {For ( i , 1 , n ) scanf ( "%d" , &s[i] ) ;For ( i , 1 , m ) scanf ( "%d" , &p[i] ) ;get_next () ;get_kmp () ;}int main () {while ( ~scanf ( "%d%d" , &n , &m ) ) solve () ;return 0 ;}

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