Submission #68851

#	Time	Username	Problem	Language	Result	Execution time	Memory
68851		duality	Bulldozer (JOI17_bulldozer)	C++11	100 / 100	1292 ms	17128 KiB

bulldozer

#include <bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
typedef long long int LLI;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vpii;
const double PI = acos(-1.0);
#define x first
#define y second

struct point { int x,y,w; };
bool comp(point a,point b) {
    if (a.y == b.y) return a.x > b.x;
    else return a.y < b.y;
}
point p[2000];
struct event { int i,j; };
vector<event> events;
LLI cross(event a,event b) {
    pii av = mp(p[a.j].x-p[a.i].x,p[a.j].y-p[a.i].y);
    pii bv = mp(p[b.j].x-p[b.i].x,p[b.j].y-p[b.i].y);
    return (LLI) av.x*bv.y-(LLI) av.y*bv.x;
}
bool comp2(event a,event b) {
    LLI c = cross(a,b);
    if (c == 0) {
        if (a.i == b.i) return a.j < b.j;
        else return a.i < b.i;
    }
    else return c > 0;
}
int arr[2000],pos[2000];
LLI sum[1 << 12],pre[1 << 12],suff[1 << 12],vec[1 << 12];
int update(int s,int e,int ai,int i,int num) {
    if ((s > ai) || (e < ai)) return 0;
    else if (s == e) {
        sum[i] = num;
        pre[i] = suff[i] = vec[i] = max(num,0);
        return 0;
    }

    int mid = (s+e) / 2;
    update(s,mid,ai,2*i+1,num);
    update(mid+1,e,ai,2*i+2,num);
    sum[i] = sum[2*i+1] + sum[2*i+2];
    pre[i] = max(pre[2*i+1],sum[2*i+1]+pre[2*i+2]);
    suff[i] = max(suff[2*i+2],sum[2*i+2]+suff[2*i+1]);
    vec[i] = max(max(vec[2*i+1],vec[2*i+2]),suff[2*i+1]+pre[2*i+2]);
    return 0;
}
int main() {
    int i;
    int N;
    scanf("%d",&N);
    for (i = 0; i < N; i++) scanf("%d %d %d",&p[i].x,&p[i].y,&p[i].w);
    sort(p,p+N,comp);

    int j;
    for (i = 0; i < N; i++) {
        for (j = i+1; j < N; j++) events.pb((event){i,j});
        arr[i] = p[i].w,pos[i] = i;
        update(0,N-1,i,0,p[i].w);
    }
    LLI ans = vec[0];
    sort(events.begin(),events.end(),comp2);
    for (i = 0; i < events.size(); i++) {
        swap(arr[pos[events[i].i]],arr[pos[events[i].j]]);
        swap(pos[events[i].i],pos[events[i].j]);
        update(0,N-1,pos[events[i].i],0,arr[pos[events[i].i]]);
        update(0,N-1,pos[events[i].j],0,arr[pos[events[i].j]]);
        if ((i == events.size()-1) || (cross(events[i],events[i+1]) != 0)) ans = max(ans,vec[0]);
    }
    printf("%lld\n",ans);

    return 0;
}

Compilation message (stderr)

bulldozer.cpp: In function 'int main()':
bulldozer.cpp:68:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i = 0; i < events.size(); i++) {
                 ~~^~~~~~~~~~~~~~~
bulldozer.cpp:73:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if ((i == events.size()-1) || (cross(events[i],events[i+1]) != 0)) ans = max(ans,vec[0]);
              ~~^~~~~~~~~~~~~~~~~~
bulldozer.cpp:56:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&N);
     ~~~~~^~~~~~~~~
bulldozer.cpp:57:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for (i = 0; i < N; i++) scanf("%d %d %d",&p[i].x,&p[i].y,&p[i].w);
                             ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 20 / 20
• Subtask 3: 35 / 35
• Subtask 4: 20 / 20
• Subtask 5: 20 / 20