Time Limit: 10000/5000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 2742 Accepted Submission(s): 980
/*
HDU 5726 GCD 区间GCD=k的个数
problem:
给你一列数字,然后是m个询问,每次询问区间[l,r]的gcd以及整个序列中有多少个区间的gcd与之相等
solve:
第一个可以通过线段树或者类rmq的方法来解决.但是求区间的个数就不知怎么弄了- -
最开始想的是每次询问求出值之后用 二分+枚举右端点 的思路来查找有多少个区间的
但是发现整个是递减的,感觉很难确定区间的大小,卒.
看别人题解才发现可以预处理,就一个左端点l而言,[l+1,n]中的到l的区间gcd是递减的.
例:
GCD[l,j] = 4,GCD[l,j+1] = 4,GCD[l,j+2] = 2
感觉题解相当于枚举以l为左点的所有区间GCD值,然后二分到当前GCD值的最右点,计算出区间的个数
因此会涉及很多次区间GCD查询,用线段树的话超时,用RMQ实现O(1)的查询AC
至于时间复杂度, 并不会算QAQ
hhh-2016-08-15 21:35:11
*/
#include <algorithm>
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <map>
#define lson i<<1
#define rson i<<1|1
#define ll long long
#define key_val ch[ch[root][1]][0]
using namespace std;
const int maxn = 100010;
const int inf = 0x3f3f3f3f;
int a[maxn];
int m[maxn];
int dp[maxn][20];
ll gcd(ll a,ll b)
{
if(b==0) return a;
else return gcd(b,a%b);
}
void iniRMQ(int n,int c[])
{
m[0] = -1;
for(int i = 1; i <= n; i++)
{
m[i] = ((i&(i-1)) == 0)? m[i-1]+1:m[i-1];
dp[i][0] = c[i];
}
for(int j = 1; j <= m[n]; j++)
{
for(int i = 1; i+(1<<j)-1 <= n; i++)
dp[i][j] = gcd(dp[i][j-1],dp[i+(1<<(j-1))][j-1]);
}
}
int RMQ(int x,int y)
{
int k = m[y-x+1];
return gcd(dp[x][k],dp[y-(1<<k)+1][k]);
}
map<int,ll>mp;
void ini(int n)
{
mp.clear();
for(int i = 1;i <= n;i++)
{
int now = a[i],j = i;
while(j <= n)
{
int l = j,r = n;
while(l < r)
{
int mid = (l+r+1) >> 1;
if(RMQ(i,mid) == now)
l = mid;
else
r = mid-1;
}
mp[now] += (ll)(l-j+1);
j = l+1;
now = RMQ(i,j);
}
}
}
int main()
{
int T,n,m;
int cas = 1;
// freopen("in.txt","r",stdin);
scanf("%d",&T);
while(T--)
{
printf("Case #%d:\n",cas++);
scanf("%d",&n);
for(int i = 1; i <= n; i++)
{
scanf("%d",&a[i]);
}
iniRMQ(n,a);
ini(n);
scanf("%d",&m);
int a,b;
for(int i =1; i <= m; i++)
{
scanf("%d%d",&a,&b);
int ans1 = RMQ(a,b);
printf("%d %I64d\n",ans1,mp[ans1]);
}
}
return 0;
}
原文:http://www.cnblogs.com/Przz/p/5792152.html