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UVALive - 4108
Description 
The skyline of Singapore as viewed from the Marina Promenade (shown on the left) is one of the iconic scenes of Singapore. Country X would also like to create an iconic skyline, and it has put up a call for proposals. Each submitted proposal is a description of a proposed skyline and one of the metrics that country X will use to evaluate a proposed skyline is the amount of overlap in the proposed sky-line.
As the assistant to the chair of the skyline evaluation committee, you have been tasked with determining the amount of overlap in each proposal. Each proposal is a sequence of buildings, The skyline formed by the first k <tex2html_verbatim_mark>buildings is the union of the rectangles of the first k <tex2html_verbatim_mark>buildings (see Figure 4). The overlap of a building, bi <tex2html_verbatim_mark>, is defined as the total horizontal length of the parts of bi <tex2html_verbatim_mark>, whose height is greater than or equal to the skyline behind it. This is equivalent to the total horizontal length of parts of the skyline behind bi<tex2html_verbatim_mark>which has a height that is less than or equal to hi <tex2html_verbatim_mark>, where hi <tex2html_verbatim_mark>is the height of building bi <tex2html_verbatim_mark>. You may assume that initially the skyline has height zero everywhere.
Input The input consists of a line containing the number c <tex2html_verbatim_mark>of datasets, followed by c <tex2html_verbatim_mark>datasets, followed by a line containing the number ` 0‘. The first line of each dataset consists of a single positive integer, n <tex2html_verbatim_mark>(0 < n < 100000) <tex2html_verbatim_mark>, which is the number of buildings in the proposal. The following n<tex2html_verbatim_mark>lines of each dataset each contains a description of a single building. The i <tex2html_verbatim_mark>-th line is a description of building bi <tex2html_verbatim_mark>. Each building bi <tex2html_verbatim_mark>is described by three positive integers, separated by spaces, namely, li <tex2html_verbatim_mark>, ri <tex2html_verbatim_mark>and hi <tex2html_verbatim_mark>, where li <tex2html_verbatim_mark>and rj <tex2html_verbatim_mark>(0 < li < ri
Output The output consists of one line for each dataset. The c <tex2html_verbatim_mark>-th line contains one single integer, representing the amount of overlap in the proposal for dataset c<tex2html_verbatim_mark>. You may assume that the amount of overlap for each dataset is at most 2000000.
Sample Input
1 3 5 11 3 1 10 1 3 13 2 0
Sample Output
14 |
题意：在线区间[l,r]查询h是最大值的长度，并更新
很明显区间max
但怎么找这个长度overlap呢？
如果当前区间满足ql<=l&&r<=qr&&h>=t[o].mx 那么就可以被完全覆盖
用lazy维护区间完全覆盖中的最大值，h<t[o].lazy时就不用继续找了(因为h不可能覆盖这个区间了)，有点像个剪枝
否则必须继续找，下传lazy(无需清空自己的标记,剪枝嘛)，合并mx
lazy和mx还有点小细节，比如paint没有用lazy更新mx，其实这不影响，因为先if(h<t[o].lazy) return;了
注意点是区间[i,i+1]
#include <iostream> #include <cstdio> #include <algorithm> #include <cstring> #define m (l+r)/2 #define lson o<<1,l,m #define rson o<<1|1,m+1,r #define lc o<<1 #define rc o<<1|1 using namespace std; typedef long long ll; const int N=1e5+5; inline int read(){ char c=getchar();int x=0,f=1; while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=getchar();} while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘;c=getchar();} return x*f; } int T,n,ql,qr,h; struct node{ int mx,lazy;//totally cover }t[N<<2]; inline void pushDown(int o){ if(t[o].lazy>t[lc].lazy) t[lc].lazy=t[o].lazy; if(t[o].lazy>t[rc].lazy) t[rc].lazy=t[o].lazy; } int lap=0; inline void update(int o,int l,int r,int ql,int qr,int h){ if(h<t[o].lazy) return; if(ql<=l&&r<=qr&&h>=t[o].mx){ t[o].mx=t[o].lazy=h; lap+=r-l+1; }else{ pushDown(o); if(ql<=m) update(lson,ql,qr,h); if(m<qr) update(rson,ql,qr,h); t[o].mx=max(t[lc].mx,t[rc].mx); } } int main(){ T=read(); while(T--){ n=read(); int ans=0; memset(t,0,sizeof(t)); for(int i=1;i<=n;i++){ ql=read();qr=read()-1;h=read(); lap=0; update(1,1,1e5,ql,qr,h); //printf("lap %d\n",lap); ans+=lap; } printf("%d\n",ans); } }
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原文地址：http://www.cnblogs.com/candy99/p/5962412.html
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