概述
Simon has an array a1, a2, ..., an, consisting of n positive integers. Today Simon asked you to find a pair of integers l, r (1 ≤ l ≤ r ≤ n), such that the following conditions hold:
- there is integer j (l ≤ j ≤ r), such that all integers al, al + 1, ..., ar are divisible by aj;
- value r - l takes the maximum value among all pairs for which condition 1 is true;
Help Simon, find the required pair of numbers (l, r). If there are multiple required pairs find all of them.
The first line contains integer n (1 ≤ n ≤ 3·105).
The second line contains n space-separated integers a1, a2, ..., an(1 ≤ ai ≤ 106).
Print two integers in the first line — the number of required pairs and the maximum value of r - l. On the following line print all l values from optimal pairs in increasing order.
5
4 6 9 3 6
1 3
2
5
1 3 5 7 9
1 4
1
5
2 3 5 7 11
5 0
1 2 3 4 5
In the first sample the pair of numbers is right, as numbers 6, 9, 3 are divisible by 3.
In the second sample all numbers are divisible by number 1.
In the third sample all numbers are prime, so conditions 1 and 2 are true only for pairs of numbers (1, 1), (2, 2), (3, 3), (4, 4), (5, 5).
【分析】给定一个正整数数组,求最长的区间,使得该区间内存在一个元素,它能整除该区间的每个元素。
可能我的方法有点复杂吧。我是先从小到大排序,记录所有数的位置,然后从小到大向两边扩展,就行了,详细见代码一。还有种做法类似DP,很短很神奇,见代码二。
#include <iostream> #include <cstring> #include <cstdio> #include <algorithm> #include <cmath> #include <string> #include <map> #include <stack> #include <queue> #include <vector> #define inf 0x3f3f3f3f #define met(a,b) memset(a,b,sizeof a) #define pb push_back #define mp make_pair typedef long long ll; using namespace std; const int N = 3e5+10; const int M = 1e6+10; int n,m,k,tot=0,tim=0; int head[N],vis[N],l[N],r[N]; int a[N],b[N]; vector<pair<int,int> >vec; vector<int>Ans; struct man{ int l,r,len; }ans[N]; bool cmp(man s,man d){ return s.len>d.len; } void Find(int p) { vis[p]=1; int ret=0; int u=b[p]; int ll,rr; ++tot; for(int i=1; i<=n; i++) { if(!l[tot]) { ll=p-i; if(ll>=1&&b[ll]%u==0) { vis[ll]=1; } else l[tot]=ll+1,ret++; } if(!r[tot]) { rr=p+i; if(rr<=n&&b[rr]%u==0) { vis[rr]=1; } else r[tot]=rr-1,ret++; } if(ret==2)return; } } int main() { scanf("%d",&n); for(int i=1; i<=n; i++) { scanf("%d",&a[i]); b[i]=a[i]; vec.pb(mp(a[i],i)); } sort(vec.begin(),vec.end()); for(int i=0;i<n;i++){ int p=vec[i].second; if(!vis[p])Find(p); } for(int i=1; i<=tot; i++) { ans[i-1].l=l[i]; ans[i-1].r=r[i]; ans[i-1].len=r[i]-l[i]; } sort(ans,ans+tot,cmp); int t=ans[0].len,ret=0; for(int i=0;i<tot;i++){ if(ans[i].len<t)break; ret++; } printf("%d %dn",ret,t); for(int i=0;i<ret;i++){ Ans.pb(ans[i].l); } sort(Ans.begin(),Ans.end()); for(int i=0;i<ret;i++){ printf("%d ",Ans[i]); } printf("n"); return 0; }
#include <iostream> #include <cstring> #include <cstdio> #include <algorithm> #include <cmath> #include <string> #include <map> #include <stack> #include <queue> #include <vector> #define inf 0x3f3f3f3f #define met(a,b) memset(a,b,sizeof a) #define pb push_back typedef long long ll; using namespace std; const int N = 2e6+10; const int M = 1e6+10; int n,L,R,len,Ans,xllend3; int a[N],ans_l[N],ans_r[N],ans[N]; void init() { scanf("%d",&n); for(int i=1; i<=n; ++i)scanf("%d",&a[i]),ans_l[i]=ans_r[i]=i; } void work() { for(int i=1; i<=n; ++i)for(; ans_l[i]>1&&a[ans_l[i]-1]%a[i]==0;)ans_l[i]=ans_l[ans_l[i]-1]; for(int i=n; i>=1; --i)for(; ans_r[i]<n&&a[ans_r[i]+1]%a[i]==0;)ans_r[i]=ans_r[ans_r[i]+1]; for(int i=1; i<=n; ++i) { L=ans_l[i]; R=ans_r[i]; if(R-L==len)ans[++Ans]=L; if(R-L>len)len=R-L,ans[Ans=1]=L; } } void outit() { sort(ans+1,ans+Ans+1); for(int i=1; i<=Ans; ++i)if(ans[i]!=ans[i-1])++xllend3; printf("%d %dn%d",xllend3,len,ans[1]); for(int i=2; i<=Ans; ++i)if(ans[i]!=ans[i-1])printf(" %d",ans[i]); puts(""); } int main() { init(); work(); outit(); return 0; }
转载于:https://www.cnblogs.com/jianrenfang/p/6479174.html
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