hdu1025-Constructing Roads In JGShining's Kingdom

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http://acm.hdu.edu.cn/showproblem.php?pid=1025

最长上升子序列（长度）

#include<iostream>#include<cstdio>#include<cstring>using namespace std; int n ;const int maxn = 500005 ;int dp[ maxn ] , a[ maxn ];int LIS(int n ){int low , len , high , mid ;len = 1 ;//mid = ( low + high ) / 2 ;dp[ 1 ] = a[ 1 ] ;for( int i = 2 ; i <= n ; i++ ){low = 1 ;high = len ;while( low <= high ){mid = ( low + high ) / 2 ;if( a[ i ] > dp[ mid ] ) low = mid + 1 ;elsehigh = mid - 1 ;}dp[ low ] = a[ i ] ;if( low > len )len = low ;}return len ;} int main(){int i , j , n ;int flag = 1 ;while( ~scanf( "%d" , &n )  ){memset( dp , 0 ,sizeof( dp ) ) ;memset( a , 0 ,sizeof( a ) ) ;for( i = 0 ; i < n ; ++i ){int x , y ;scanf( "%d%d" , &x , &y );a[ x ] = y ;}int ans = LIS( n ) ;printf( "Case %d:\n" , flag++ ) ;if( ans == 1 )printf( "My king, at most 1 road can be built.\n" ) ;elseprintf( "My king, at most %d roads can be built.\n" , ans ) ;printf( "\n" ) ;}return 0  ;}