POJ 2482 Stars in Your Window(线段树+扫描线)

题目链接

非常不容易的一道题，把每个点向右上构造一个矩形，将问题转化为重合矩形那个亮度最大，注意LL，注意排序。

 #include <cstdio>
 #include <cstring>
 #include <string>
 #include <algorithm>
 using namespace std;
 #define maxn 50100
 #define lson l,m,rt<<1
 #define rson m+1,r,rt<<1|1
 #define LL __int64
 struct node
 {
     LL lx,rx,y;
     LL s;
     node(){}
     node(LL a,LL b,LL c,LL d):lx(a),rx(b),y(c),s(d){}
     bool operator < (const node &S) const
     {
         if(y == S.y)
         return s > S.s;
         else
         return y < S.y;
     }
 }mat[maxn];
 LL que[*maxn];
 LL tree[*maxn];
 LL lz[*maxn];
 void pushup(int rt)
 {
     tree[rt] = max(tree[rt<<],tree[rt<<|]);
 }
 void pushdown(int rt)
 {
     if(lz[rt])
     {
         lz[rt<<] += lz[rt];
         lz[rt<<|] += lz[rt];
         tree[rt<<] += lz[rt];
         tree[rt<<|] += lz[rt];
         lz[rt] = ;
     }
 }
 void update(int L,int R,int c,int l,int r,int rt)
 {
     int m;
     if(L <= l&&r <= R)
     {
         tree[rt] += c;
         lz[rt] += c;
         return ;
     }
     pushdown(rt);
     m = (l+r)>>;
     if(L <= m)
     update(L,R,c,lson);
     if(R > m)
     update(L,R,c,rson);
     pushup(rt);
 }
 int bin(LL x,int n)
 {
     int str,mid,end;
     str = ;
     end = n;
     while(str <= end)
     {
         mid = (str+end)/;
         if(que[mid] == x)
         return mid;
         else if(que[mid] > x)
         end = mid - ;
         else
         str = mid + ;
     }
     return mid;
 }
 int main()
 {
     int n,num,k,i;
     LL a,b,c,h,w;
     while(scanf("%d%I64d%I64d",&n,&w,&h)!=EOF)
     {
         num = ;
         w--;
         h--;
         for(i = ;i < n;i ++)
         {
             scanf("%I64d%I64d%I64d",&a,&b,&c);
             mat[num] = node(a,a+w,b,c);
             que[num++] = a;
             mat[num] = node(a,a+w,b+h,-c);
             que[num++] = a+w;
         }
         k = ;
         sort(que,que+num);
         sort(mat,mat+num);
         for(i = ;i < num;i ++)
         {
             if(que[i] != que[i-])
             que[k++] = que[i];
         }
         LL maxz = ;
         memset(tree,,sizeof(tree));
         memset(lz,,sizeof(lz));
         for(i = ;i < num;i ++)
         {
             int l = bin(mat[i].lx,k-);
             int r = bin(mat[i].rx,k-);
             if(l <= r) update(l,r,mat[i].s,,k-,);
             maxz = max(maxz,tree[]);
         }
         printf("%I64d\n",maxz);
     }
     return ;
 }