[APIO2014]序列分割

#include<bits/stdc++.h>
#define RG register
#define IL inline
#define _ 150005
#define eps 1e-7
#define ll long long
using namespace std; 
 
ll n , K , s[_] , a[_] , C , inf , Res , L , R , hd , tl ;  
struct Item{
    ll id , from , sum , v; 
    IL Item(){id = from = sum = v = 0 ; }  
};
Item operator + (const Item A , const Item B) {
    Item tmp ; tmp.id = A.id ; 
    tmp.from = B.id ; tmp.sum = B.sum + 1 ;
    tmp.v = B.v + s[B.id] * (s[A.id] - s[B.id]) + C ; 
    return tmp ; 
}

struct Solver{ 
    Item f[_] , que[_] ; ll ans[_] , tot ; ll Result ; 	
    IL double Slope(Item A , Item B){
        RG double Dy = (A.v - s[A.id]*s[A.id]) - (B.v - s[B.id]*s[B.id]) ; 
        RG double Dx = s[A.id] - s[B.id] ;  
        if(fabs(Dy) <= eps) return 0 ; 
        return 1.0 * Dy / Dx ; 
    }		
    IL ll solve(){
        hd = 1; tl = 1;  
        f[0].id = f[0].sum = f[0].from = f[0].v = 0 ;
        que[hd].id = que[hd].sum = que[hd].v = que[hd].from = 0 ; 
        for(RG int i = 1; i <= n; i ++){
            f[i].id = i ;
     		while(hd < tl && Slope(que[hd + 1] , que[hd]) >= -s[i]) ++ hd;
        	f[i] = f[i] + que[hd] ; 
            while(hd < tl && Slope(f[i] , que[tl - 1]) >= Slope(que[tl] , que[tl - 1])) -- tl; 
            que[++tl] = f[i] ;
        }
        return f[n].sum - 1 <= K;
    }
    
    IL void Get(){
        Result = f[n].v - (K + 1) * Res; 
        tot = 0 ; 
        for(RG int e = f[n].from; e ; e = f[e].from) ans[++tot] = e ;  		
    }
    IL void PutOut(){
        cout << Result << endl;
        for(RG int i = tot ; i >= 1 ; i --) cout << ans[i] << " " ;  
    }
}E;

int main(){
    std::ios::sync_with_stdio(false) ; 
    cin >> n >> K ;  
    for(RG int i = 1; i <= n; i ++) cin >> a[i] ; 
    for(RG int i = 1; i <= n; i ++) s[i] = s[i - 1] + a[i] ;
    inf = 1e15 ;  L = -inf ; R = inf ; Res = 0 ; 
    while(L <= R){
        C = (L + R) >> 1 ; 
        if(E.solve()) Res = C , E.Get() ,  L = C + 1 ; 
        else R = C - 1 ; 
    }
    E.PutOut() ; return 0 ; 
}