haha，贪心，边界条件折腾了我一会儿
1 #include<cstdio>
2 #include<cctype>
3 #include<queue>
4 #include<algorithm>
5 using namespace std ;
6
7 const int MAXN = 1000000 + 200 ;
8 int N , K ;
9 int dis [ MAXN ] ;
10 int l [ MAXN ] ;
11 int r [ MAXN ] ;
12 int v [ MAXN ] ;
13 int vis [ MAXN ] ;
14 int ans ;
15 struct cmp {
16 bool operator () ( const int a , const int b ) { return v [ a ] > v [ b ] ; } ;
17 } ;
18 priority_queue < int , vector < int > , cmp > q ;
19
20 int main () {
21 scanf ( "%d%d" , & N , & K ) ;
22 for ( int i = 1 ; i <= N ; ++ i ) scanf ( "%d" , dis + i ) ;
23 for ( int i = 1 ; i < N ; ++ i ) v [ i ] = dis [ i + 1 ] - dis [ i ] ;
24 for ( int i = 1 ; i < N - 1 ; ++ i ) r [ i ] = i + 1 ;
25 for ( int i = 2 ; i < N ; ++ i ) l [ i ] = i - 1 ;
26 for ( int i = 1 ; i < N ; ++ i ) q . push ( i ) ;
27 fill_n ( vis + 1 , N , 1 ) ;
28 v [ 0 ] = 1000000000 + 1 ;
29 v [ N ] = 1000000000 + 1;
30 while ( K -- ) {
31 while ( ! vis [ q . top () ] ) q . pop () ;
32 const int o = q . top () ; q . pop () ;
33 ans += v [ o ] ;
34 vis [ l [ o ] ] = 0 ;
35 vis [ r [ o ] ] = 0 ;
36 v [ o ] = v [ l [ o ] ] + v [ r [ o ] ] - v [ o ] ;
37 q . push ( o ) ;
38 l [ o ] = l [ l [ o ] ] ; r [ o ] = r [ r [ o ] ] ;
39 r [ l [ o ] ] = l [ r [ o ] ] = o ;
40 }
41 printf ( "%d\n" , ans ) ;
42 }
