제출 #1303236

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1303236		trandangquang	Feast (NOI19_feast)	C++20	100 / 100	212 ms	137224 KiB

feast

#include<bits/stdc++.h>
using namespace std;

#define foru(i,a,b) for(int i=(a); i<=(b); ++i)
#define ford(i,a,b) for(int i=(a); i>=(b); --i)
#define rep(i,a) for(int i=0; i<(a); ++i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(),(a).end()
#define bit(s,i) (((s)>>(i))&1)
#define ii pair<int,int>
#define vi vector<int>
#define vii vector<ii>
#define fi first
#define se second
#define ll long long
#define eb emplace_back
#define pb push_back
#define __builtin_popcount __builtin_popcountll
#define _ << " " <<

template <class X, class Y> bool maxi(X &x, Y y){return x<y?x=y,true:false;}
template <class X, class Y> bool mini(X &x, Y y){return x>y?x=y,true:false;}

const int N=3e5+5;

int n,k,a[N];

struct Node{
    ll mx; int l, r; /// max trong doan
    ll mxp; int p; /// max prefix
    ll mxs; int s; /// max suffix
    ll sum;
    /// cac doan co it nhat 1 phan tu

    Node(){
        mx=mxp=mxs=sum=0;
        l=r=p=s=0;
    }
} stP[N<<2], stN[N<<2];

Node comb(Node a, Node b){
    Node c;
    c.mx=max(max(a.mx,b.mx),a.mxs+b.mxp);
    if(c.mx==a.mx) c.l=a.l, c.r=a.r;
    else if(c.mx==b.mx) c.l=b.l, c.r=b.r;
    else c.l=a.s, c.r=b.p;

    c.mxp=max(a.mxp, a.sum+b.mxp);
    if(c.mxp==a.mxp) c.p=a.p;
    else c.p=b.p;

    c.mxs=max(b.mxs, b.sum+a.mxs);
    if(c.mxs==b.mxs) c.s=b.s;
    else c.s=a.s;

    c.sum=a.sum+b.sum;

    return c;
}

#define lc id<<1
#define rc id<<1|1

void build(int id=1, int l=1, int r=n){
    if(l==r){
        stP[id].mx=stP[id].mxp=stP[id].mxs=stP[id].sum=a[l];
        stP[id].l=stP[id].r=stP[id].p=stP[id].s=l;

        stN[id].mx=stN[id].mxp=stN[id].mxs=stN[id].sum=-a[l];
        stN[id].l=stN[id].r=stN[id].p=stN[id].s=l;
        return;
    }
    int mid=(l+r)>>1;
    build(lc,l,mid);
    build(rc,mid+1,r);
    stP[id]=comb(stP[lc],stP[rc]);
    stN[id]=comb(stN[lc],stN[rc]);
}

int lz[N<<2];
void apply(int id){
    lz[id]^=1;
    swap(stP[id],stN[id]);
}
void down(int id){
    if(lz[id]==0)return;
    apply(lc); apply(rc);
    lz[id]=0;
}
void upd(int u, int v, int id=1, int l=1, int r=n){
    if(u>r||v<l)return;
    if(u<=l&&r<=v){
        apply(id);
        return;
    }
    int mid=(l+r)>>1;
    down(id);
    upd(u,v,lc,l,mid);
    upd(u,v,rc,mid+1,r);
    stP[id]=comb(stP[lc],stP[rc]);
    stN[id]=comb(stN[lc],stN[rc]);
}

void solve(){
    cin>>n>>k;
    foru(i,1,n) cin>>a[i];

    build();

    ll res=0, cur=0;
    foru(i,1,k){
        int l=stP[1].l, r=stP[1].r;
        cur+=stP[1].mx;

        upd(l,r);
        maxi(res,cur);
    }
    cout<<res<<'\n';
}

int32_t main(){
    #define task "test"
    if(fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    cin.tie(0)->sync_with_stdio(0);

    int tc=1; //cin>>tc;
    foru(i,1,tc){
        solve();
    }
}

컴파일 시 표준 에러 (stderr) 메시지

feast.cpp: In function 'int32_t main()':
feast.cpp:124:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  124 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:125:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  125 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29