【CodeForces】463D Gargari and Permutations DP

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传送门：【CodeForces】463D Gargari and Permutations

题目分析：对于所有的数对(x,y)如果x在所有的串中都排在y的前面，则建边(x,y)，最后跑一遍最长路，最长路的长度就是答案。

代码如下：

#include <cmath>#include <cstdio>#include <cstring>#include <algorithm>using namespace std ;#define REP( i , a , b ) for ( int i = ( a ) ; i <  ( b ) ; ++ i )#define FOR( i , a , b ) for ( int i = ( a ) ; i <= ( b ) ; ++ i )#define REV( i , a , b ) for ( int i = ( a ) ; i >= ( b ) ; -- i )#define travel( e , H , u ) for ( Edge* e = H[u] ; e ; e = e -> next )#define CLR( a , x ) memset ( a , x , sizeof a )typedef long long LL ;const int MAXN = 1005 ;const int MAXE = 1000005 ;struct Edge {int v ;Edge* next ;} E[MAXE] , *H[MAXN] , *cur ;int G[MAXN][MAXN] ;int d[MAXN] ;int in[MAXN] ;int Q[MAXN] , head , tail ;int n , k ;int s[MAXN] ;void clear () {cur = E ;CLR ( H , 0 ) ;CLR ( G , 0 ) ;CLR ( d , 0 ) ;CLR ( in , 0 ) ;head = tail = 0 ;}void addedge ( int u , int v ) {cur -> v = v ;cur -> next = H[u] ;H[u] = cur ++ ;}void topo () {FOR ( i , 1 , MAXN ) if ( !in[i] ) d[i] = 1 , Q[tail ++] = i ;while ( head != tail ) {int u = Q[head ++] ;travel ( e , H , u ) {int v = e -> v ;if ( d[v] < d[u] + 1 ) d[v] = d[u] + 1 ;if ( -- in[v] == 0 ) Q[tail ++] = v ;}}}void solve () {int ans = 0 ;clear () ;FOR ( _ , 1 , k ) {FOR ( i , 1 , n ) {scanf ( "%d" , &s[i] ) ;REP ( j , 1 , i ) ++ G[s[j]][s[i]] ;}}FOR ( i , 1 , n ) FOR ( j , 1 , n ) if ( G[i][j] == k ) addedge ( i , j ) , ++ in[j] ;topo () ;FOR ( i , 1 , n ) if ( d[i] > ans ) ans = d[i] ;printf ( "%d\n" , ans ) ;}int main () {while ( ~scanf ( "%d%d" , &n , &k ) ) solve () ;return 0 ;}

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