【HDU】1828 Picture

 1 #include<cstdio>

 2 #include<cstring>

 3 #include<cstdlib>

 4 #include<algorithm>

 5 #define MAXN 20010

 6 #define INF 123456789

 7 using namespace std;

 8 struct Line

 9 {

10     int left,right,high,flag;

11 };

12 Line p[MAXN];

13 struct node

14 {

15     int sum,cnt,left,right,vertical;

16 }tree[MAXN<<2];

17 int cmp(const void *a,const void *b)

18 {

19     return (*(Line *)a).high-(*(Line *)b).high;

20 }

21 inline void PushUp(int L,int R,int rt)

22 {

23     if(tree[rt].cnt)

24     {

25         tree[rt].sum=R-L+1;

26         tree[rt].left=tree[rt].right=1;

27         tree[rt].vertical=2;

28     }

29     else if(L==R)

30         tree[rt].sum=tree[rt].left=tree[rt].right=tree[rt].vertical=0;

31     else

32     {

33         tree[rt].sum=tree[rt<<1].sum+tree[rt<<1|1].sum;

34         tree[rt].left=tree[rt<<1].left;

35         tree[rt].right=tree[rt<<1|1].right;

36         tree[rt].vertical=tree[rt<<1].vertical+tree[rt<<1|1].vertical;

37         if(tree[rt<<1].right&&tree[rt<<1|1].left)

38             tree[rt].vertical-=2;

39     }

40 }

41 void Update(int x,int y,int flag,int L,int R,int rt)

42 {

43     if(x<=L&&R<=y)

44     {

45         tree[rt].cnt+=flag;

46         PushUp(L,R,rt);

47     }

48     else

49     {

50         int mid=(L+R)>>1;

51         if(mid>=x)

52             Update(x,y,flag,L,mid,rt<<1);

53         if(y>mid)

54             Update(x,y,flag,mid+1,R,rt<<1|1);

55         PushUp(L,R,rt);

56     }

57 }

58 int main()

59 {

60     int ans,i,n,x1,y1,x2,y2,left,right,cnt,last;

61     while(~scanf("%d",&n))

62     {

63         left=INF;

64         right=-INF;

65         for(i=cnt=0;i<n;i++)

66         {

67             scanf("%d%d%d%d",&x1,&y1,&x2,&y2);

68             p[cnt].left=x1;

69             p[cnt].right=x2;

70             p[cnt].flag=1;

71             p[cnt++].high=y1;

72             p[cnt].left=x1;

73             p[cnt].right=x2;

74             p[cnt].flag=-1;

75             p[cnt++].high=y2;

76             left=min(left,x1);

77             right=max(right,x2);

78         }

79         qsort(p,cnt,sizeof(p[0]),cmp);

80         memset(tree,0,sizeof(tree));

81         for(ans=last=i=0;i<cnt;i++)

82         {

83             Update(p[i].left,p[i].right-1,p[i].flag,left,right-1,1);

84             ans+=abs(tree[1].sum-last);

85             last=tree[1].sum;

86             if(i<cnt-1)

87                 ans+=(p[i+1].high-p[i].high)*tree[1].vertical;

88         }

89         printf("%d\n",ans);

90     }

91     return 0;

92 }