[Data structure-segment tree] POJ 2528

Put a poster on one wall, the order of the stickers given, the number of posters to be seen at the end.

Pure line Tree simulation problem.

But the data range gives 10^7, hyper-memory.

In fact, here is a small trick, although the width of the wall is very large, but the number of posters is only 10000, so the number of 10^7 really few, so that only the number of useless to "delete", the remaining number from small to large mapping for the new number, so that the space complexity is greatly reduced.

For example, a sample of the topic:

1 42 68 103 47 10

Number of uses: 1 2 3 4 6 7 8 10

You can map them to:

1	2	3	4	6	7	8	10
1	2	3	4	5	6	7	8

This will only open to 8 when the achievement of the line.

#include <iostream>#include<algorithm>#include<cstring>#include<cstdio>using namespacestd;Const intmaxn=20010;intseg[maxn*2];//the node number of the segment tree starts at 0. intlnext[maxn*2],rnext[maxn*2];intl[maxn*2],r[maxn*2];inttot;intBuildtree (intllintRR) {    intcur=tot++; L[cur]=ll; R[cur]=RR; if(ll==RR) {Seg[cur]=0; //printf ("%d**\n", Seg[cur]);lnext[cur]=rnext[cur]=-1; returncur; }    intMid= (LL+RR) >>1; Lnext[cur]=Buildtree (Ll,mid); Rnext[cur]=buildtree (mid+1, RR); Seg[cur]=0; returncur;}BOOLAddintCurintllintRrintval) {    if(rnext[cur]!=-1&&lnext[cur]&&seg[rnext[cur]]&&Seg[lnext[cur]]) {Seg[cur]=1; }    if(Seg[cur])return false; if(ll>RR) swap (LL,RR); if(l[cur]==ll&&r[cur]==RR) {Seg[cur]=Val; return true; }    BOOLs1=0, s2=0; intMID = (L[cur]+r[cur]) >>1; if(ll>=mid+1) S1=Add (Rnext[cur],ll,rr,val); Else if(rr<=mid) S2=Add (Lnext[cur],ll,rr,val); Else{S1=Add (Lnext[cur],ll,mid,val); S2=add (rnext[cur],mid+1, Rr,val); }    if(rnext[cur]!=-1&&lnext[cur]&&seg[rnext[cur]]&&Seg[lnext[cur]]) {Seg[cur]=1; }    returns1| |S2;}intdata[10005][2];inty[20005],cur,ying[10000002];intMain () {intT,n,ans; scanf ("%d",&T);  while(T--&AMP;&AMP;SCANF ("%d", &n)! =EOF) {ans=0; cur=1; tot=0;  for(intI=0; i<n;i++) {scanf ("%d%d", &data[i][0],&data[i][1]); Y[cur++]=data[i][0]; Y[cur++]=data[i][1]; } y[0]=-1; Sort (y+1, y+cur); intCc=1;  for(intI=1; i<cur;i++) {            if(y[i]==y[i-1])Continue; Ying[y[i]]=cc++; } buildtree (1, cc-1);  for(inti=n-1; i>=0; i--) {data[i][0]=ying[data[i][0]]; data[i][1]=ying[data[i][1]]; if(Add (0, data[i][0],data[i][1],1)) ans++; } printf ("%d\n", ans); }}

[Data structure-segment tree] POJ 2528