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POJ 1177 Picture

题目大意:矩形的周长并(够大意了~)


解题思路:

扫描线,跟面积并一样,只不过处理周长的时候注意边的增加与减少。



下面是代码:

#include <set>
#include <map>
#include <queue>
#include <math.h>
#include <vector>
#include <string>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <iostream>
#include <algorithm>

#define eps 1e-8
#define pi acos(-1.0)
#define inf 107374182
#define inf64 1152921504606846976
#define lc l,m,tr<<1
#define rc m + 1,r,tr<<1|1
#define iabs(x)  ((x) > 0 ? (x) : -(x))
#define clear1(A, X, SIZE) memset(A, X, sizeof(A[0]) * (SIZE))
#define clearall(A, X) memset(A, X, sizeof(A))
#define memcopy1(A , X, SIZE) memcpy(A , X ,sizeof(X[0])*(SIZE))
#define memcopyall(A, X) memcpy(A , X ,sizeof(X))
#define max( x, y )  ( ((x) > (y)) ? (x) : (y) )
#define min( x, y )  ( ((x) < (y)) ? (x) : (y) )


using namespace std;

struct node2
{
    int num;
    int y,l,r;
} edge[10005];

int tempx[10005],binx[10005];
int x1,x2,y1,y2,ans;
int cntx,n;

bool cmp(node2 a,node2 b)
{
    if(a.y==b.y)return a.num<b.num;
    return a.y<b.y;
}

int binnum(int num)
{
    int ll=0,m,rr=cntx-1;
    while(rr>ll)
    {
        m=(ll+rr)>>1;
        if(binx[m]==num)return m;
        else if(binx[m]<num)ll=m+1;
        else rr=m-1;
    }
    return ll;
}

struct node1
{
    int disnow;
    int cnt,segcnt;
    bool sta1,sta2;
} node[20000<<2];

inline void PushUp(int l,int r,int tr)
{
    if(node[tr].cnt)
    {
        node[tr].sta1=true;
        node[tr].sta2=true;
        node[tr].segcnt=1;
        node[tr].disnow=binx[r+1]-binx[l];
    }
    else if(l==r)
    {
        node[tr].disnow=0;
        node[tr].segcnt=0;
        node[tr].sta1=false;
        node[tr].sta2=false;
    }
    else
    {
        node[tr].disnow=node[tr<<1].disnow+node[tr<<1|1].disnow;

        node[tr].sta1=node[tr<<1].sta1;
        node[tr].sta2=node[tr<<1|1].sta2;
        node[tr].segcnt=node[tr<<1].segcnt+node[tr<<1|1].segcnt;
        if(node[tr<<1].sta2&&node[tr<<1|1].sta1)
        {
            node[tr].segcnt--;
        }
    }
}

void update(int L,int R,int num,int l,int r,int tr)
{
    if(L<=l&&r<=R)
    {
        node[tr].cnt+=num;
        PushUp(l,r,tr);
        return ;
    }
    int m=(l+r)>>1;
    if(L<=m)update(L,R,num,l,m,tr<<1);
    if(m<R)update(L,R,num,m+1,r,tr<<1|1);
    PushUp(l,r,tr);
}
int main()
{
    int case1=1,sta;
    int temp;
    while(scanf("%d",&n)!=EOF)
    {
        for(int i=0; i<n; i++)
        {
            scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
            tempx[2*i]=x1;
            tempx[2*i+1]=x2;
            edge[2*i].l=x1;
            edge[2*i].r=x2;
            edge[2*i+1]=edge[2*i];
            edge[2*i].y=y1;
            edge[2*i+1].y=y2;
            edge[2*i].num=1;
            edge[2*i+1].num=-1;
        }
        sort(tempx,tempx+2*n);
        binx[0]=tempx[0];
        cntx=1;
        for(int i=1; i<2*n; i++)
        {
            if(tempx[i]!=binx[cntx-1])
            {
                binx[cntx++]=tempx[i];
            }
        }
        sort(edge,edge+2*n,cmp);
        clearall(node,0);
        x1=binnum(edge[0].l);
        x2=binnum(edge[0].r);
        x2--;
        update(x1,x2,edge[0].num,0,cntx-2,1);
        y1=edge[0].y;
        sta=edge[0].num;
        ans=0;
        temp=0;
        for(int i=1; i<2*n; i++)
        {
            if(y1!=edge[i].y||sta!=edge[i].num)
            {
                ans+=iabs(node[1].disnow-temp);
                temp=node[1].disnow;
                sta=edge[i].num;
                if(y1!=edge[i].y)
                {
                    ans+=(edge[i].y-y1)*2*node[1].segcnt;
                    y1=edge[i].y;
                }
            }
            x1=binnum(edge[i].l);
            x2=binnum(edge[i].r);
            x2--;
            update(x1,x2,edge[i].num,0,cntx-2,1);
        }
        ans+=temp;
        printf("%d\n",ans);
    }
    return 0;
}


POJ 1177 Picture