hdu 1025 二分

hdu 1025 二分

#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std ;
const int maxn = 50005 ;
int dp [maxn ] , a [maxn ];
int Lis ( int n ) {
    int len = 1 , left , right , mid ;
    dp [ 1 ] = a [ 1 ];
    for ( int i = 2 ;i <=n ;i ++) {
        left = 1 ;
        right = len ;
        while (left <= right ) {
            mid = (left + right ) / 2 ;
            if (a [i ] > dp [mid ])
                left = mid + 1 ;
            else right = mid - 1 ;
        }
        dp [left ] = a [i ];
        if (left > len ) len = left ;
    }
    return len ;
}
int main () {
    int n , cas = 1 ;
    while (~scanf ( "%d" ,&n )) {
        int x , y ;
        for ( int i = 0 ;i <n ;i ++) {
            scanf ( "%d%d" ,&x ,&y );
            a [x ] = y ;
        }
        int ans = Lis (n );
        printf ( "Case %d:\n" ,cas ++);
        if (ans == 1 ) printf ( "My king, at most 1 road can be built.\n\n" );
        else printf ( "My king, at most %d roads can be built.\n\n" ,ans );
    }
    return 0 ;
}