Submission #1691589

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Source Code Expand

#include <bits/stdc++.h>
#define ls  (n<<1)
#define rs  (ls|1)
using namespace std;

const int N=300010;
struct point{int x,y;}a[N];
int w,h,n,ans,st1[N],st2[N],top1,top2,t[4*N],tag[4*N];

bool cmp(point x,point y){return x.x<y.x;}

void build(int n,int l,int r)
{
	if (l==r)  t[n]=-a[l-1].x;
	else
		{
			int mid=(l+r)>>1;
			build(ls,l,mid),build(rs,mid+1,r);
			t[n]=max(t[ls],t[rs]);
		}
}

void modify(int n,int l,int r,int L,int R,int k)
{
	if ((L<=l)&&(r<=R))  t[n]+=k,tag[n]+=k;
	else
		{
			int mid=(l+r)>>1;
			if (L<=mid)  modify(ls,l,mid,L,R,k);
			if (mid<R)  modify(rs,mid+1,r,L,R,k);
			t[n]=max(t[ls],t[rs])+tag[n];
		}
}

void solve()
{
	memset(t,0,sizeof(t)),memset(tag,0,sizeof(tag)),top1=top2=0;
	sort(a+1,a+n+1,cmp);
	if (a[n].x!=w)  a[++n]=(point){w,-1};
	build(1,1,n);
	for (int i=1; i<=n; i++)
		if (a[i].y>h/2)
			{
				modify(1,1,n,i,i,h);
				ans=max(ans,2*(a[i].x+t[1]));
				modify(1,1,n,st1[top1]+1,i,a[i].y-h);
				while ((top1)&&(a[st1[top1]].y>a[i].y))
					modify(1,1,n,st1[top1-1]+1,st1[top1],a[i].y-a[st1[top1]].y),top1--;
				st1[++top1]=i;
			}else
			{
				modify(1,1,n,i,i,h);
				ans=max(ans,2*(a[i].x+t[1]));
				modify(1,1,n,st2[top2]+1,i,-a[i].y);
				while ((top2)&&(a[st2[top2]].y<a[i].y))
					modify(1,1,n,st2[top2-1]+1,st2[top2],a[st2[top2]].y-a[i].y),top2--;
				st2[++top2]=i;
			}
	n-=(a[n].y<0);
}

void work()
{
	scanf("%d %d %d",&w,&h,&n);
	for (int i=1; i<=n; i++)  scanf("%d %d",&a[i].x,&a[i].y);
	solve();
	for (int i=1; i<=n; i++)  swap(a[i].x,a[i].y);
	swap(w,h);
	solve();
	printf("%d",ans);
}

int main()
{
	work();
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘void work()’:
./Main.cpp:64:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d",&w,&h,&n);
                            ^
./Main.cpp:65:58: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  for (int i=1; i<=n; i++)  scanf("%d %d",&a[i].x,&a[i].y);
                                                          ^

Judge Result