Codeforces Round #333 (Div. 2) 602D. Lipshitz Sequence 单调栈

#include<stdio.h>
#include<string.h>
#include<iostream>
#include<algorithm>
#include<math.h>
#include<queue>
#include<stack>
#include<string>
#include<vector>
#include<map>
#include<set>
using namespace std;
#define lowbit(x) (x&(-x))
typedef long long LL;
const int maxn = 100005;
const int inf=(1<<28)-1;
int A[maxn],stac[maxn],len,tmp[maxn];
int L[maxn],R[maxn];
int main()
{
int n,q;
scanf("%d%d",&n,&q);
for(int i=1;i<=n;++i) scanf("%d",&A[i]);
while(q--)
{
int l,r;
scanf("%d%d",&l,&r);
int tot=0;
for(int i=l;i<=r-1;++i)
tmp[++tot]=abs(A[i+1]-A[i]);
int cnt=0;
for(int i=1;i<=tot;++i)
{
while(cnt&&tmp[stac[cnt]]<=tmp[i]) cnt--;
if(cnt==0) L[i]=0;
else L[i]=stac[cnt];
stac[++cnt]=i;
}
cnt=0;
for(int i=tot;i>=1;--i)
{
while(cnt&&tmp[stac[cnt]]<tmp[i]) cnt--;
if(cnt==0) R[i]=tot+1;
else R[i]=stac[cnt];
stac[++cnt]=i;
}
LL ans=0;
for(int i=1;i<=tot;++i)
{
ans+=(LL)(i-L[i])*(R[i]-i)*tmp[i];
}
printf("%lld\n",ans);
}
return 0;
}