HDU 3450 Segment Tree + two points

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Test instructions: Give a sequence of numbers, and ask you that the absolute value of the difference between the two adjacent number is greater than 2, and the 9901

Train of thought: see not at all, did not think is the topic of line tree, weak cry ~ ~ ~, see the solution of Daniel, is to know how the matter, for the current number A, then it is the last element can be composed of the situation is a-d to a+d and, can also think, A-d has formed the M kind of situation, Then in the case of less than D, you can directly put a into the a-d composition of the left and right sequence, then directly add can, and then update A can be composed of the situation, the data is too large also need to be discretized, and then two points to find the location of a-d and A+d, the data may not have these two locations, Then find the first is greater than or equal to a-d and the first position less than or equal to a+d update on the line, and will not affect the results, I write a data to see it will understand PS: Multi-school topic is very difficult, want to brush a set of their own part of the topic, and too difficult to give up directly (after all, too weak),

#include <stdio.h> #include <string.h> #include <stdlib.h> #include <iostream> #include < Algorithm>using namespace Std;typedef Long long ll;typedef unsigned long long ull;const int Inf=0x3f3f3f3f;const ll INF =0x3f3f3f3f3f3f3f3fll;const int maxn=100010;const int mod=9901;int num[maxn<<2],a[maxn],b[maxn];int n,m;int    lower_1 (int val,int k) {int le=0,ri=k;        while (ri-le>1) {int mid= (LE+RI) >>1;        if (b[mid]<=val) Le=mid;    else Ri=mid; } return le+1;}        void update (int pos,int add,int le,int ri,int node) {if (Le==ri) {num[node]+=add;        Num[node]%=mod;    return;    } int t= (LE+RI) >>1;    if (pos<=t) update (POS,ADD,LE,T,NODE&LT;&LT;1);    else update (POS,ADD,T+1,RI,NODE&LT;&LT;1|1); Num[node]= (num[node<<1]+num[node<<1|1])%mod;}    int query (int l,int r,int le,int ri,int node) {if (l<=le&&ri<=r) return Num[node];    int ans=0,t= (LE+RI) >>1; if (l<=t) ans+=query(l,r,le,t,node<<1);    if (r>t) ans+=query (l,r,t+1,ri,node<<1|1); return ans%mod;}        int main () {while (scanf ("%d%d", &n,&m)!=-1) {int k=1,ans=0;        memset (num,0,sizeof (num));            for (int i=0;i<n;i++) {scanf ("%d", &a[i]);        B[i]=a[i];        } sort (b,b+n);        for (int i=1;i<n;i++) {if (b[i]!=b[i-1]) b[k++]=b[i];            } for (int i=0;i<n;i++) {int le=lower_bound (b,b+k,a[i]-m)-b+1;            int ri=lower_1 (A[I]+M,K);            int Pos=lower_bound (b,b+k,a[i])-b+1;            int Ans1=query (le,ri,1,k,1);            Ans= (ans+ans1)%mod;        Update (pos,ans1+1,1,k,1);    } printf ("%d\n", ans); } return 0;}

HDU 3450 Segment Tree + two points