题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=3450
4 2 1 3 7 5
4
#include <iostream> #include <stdio.h> #include <string> #include <string.h> #include <cstdio> #include <algorithm> #include <cmath> const int N=1e5+100; const int mod=9901; using namespace std; struct node { int v,id; }a[N]; bool cmp(node a,node b) { return a.v<b.v; } int n,d,c[N],b[N]; int lowbit(int x) { return x&(-x); } void update(int x,int d) { while(x<=n) { c[x]+=d; if(c[x]>mod)c[x]%=mod; x+=lowbit(x); } } int getsum(int x) { int ans=0; while(x>0) { ans+=c[x]; if(ans>mod)ans%=mod; x-=lowbit(x); } return ans; } int find(int x) { if(x>=a[n].v)return n; if(x<a[1].v)return 0; int l=1,r=n,ret=0; while(l<=r) { int mid=(l+r)/2; if(x>=a[mid].v) { ret=mid; l=mid+1; } else r=mid-1; } return ret; } int main() { while(scanf("%d%d",&n,&d)!=EOF) { memset(c,0,sizeof(c)); memset(b,0,sizeof(b)); for(int i=1;i<=n;i++) { scanf("%d",&a[i].v); a[i].id=i; } sort(a+1,a+1+n,cmp); for(int i=1;i<=n;i++)b[a[i].id]=i; int sum=0; for(int i=1;i<=n;i++) { int p=find(a[b[i]].v+d); int q=find(a[b[i]].v-d-1); int temp=getsum(p)-getsum(q); temp=(temp+mod)%mod; sum=(sum+temp)%mod; update(b[i],temp+1); } printf("%d\n",sum); } return 0; }
原文:http://blog.csdn.net/liusuangeng/article/details/39552893