玲珑杯”ACM比赛 Round #19 B 维护单调栈

 1 #pragma comment(linker, "/STACK:102400000,102400000")
 2 #include <cstdio>
 3 #include <iostream>
 4 #include <cstdlib>
 5 #include <cstring>
 6 #include <algorithm>
 7 #include <cmath>
 8 #include <cctype>
 9 #include <map>
10 #include <set>
11 #include <queue>
12 #include <bitset>
13 #include <string>
14 #include <complex>
15 #define ll long long
16 #define mod 1000000007
17 using namespace std;
18 ll n,k;
19 ll a[200005];
20 ll l[200005],r[200005];
21 map<ll,map<ll,ll>> mp;
22 int main()
23 {
24         scanf("%lld %lld",&n,&k);
25         for(int i=1; i<=n; i++)
26             scanf("%lld",&a[i]);
27         a[0]=-1ll;
28         a[n+1]=-1ll;
29         l[1]=1ll;
30         for(int i=2; i<=n; i++) //关键********
31         {
32             ll temp=i-1;
33             while(a[temp]>=a[i])//维护一个递增的序列
34                 temp=l[temp]-1;
35             l[i]=temp+1;
36         }
37         r[n]=n;
38         for (int i=n-1; i>=1; i--)
39         {
40             ll temp=i+1;
41             while(a[temp]>=a[i])
42                 temp=r[temp]+1;
43             r[i]=temp-1;
44         }
45         ll ans=0;
46         for(int i=1; i<=n; i++)
47         {
48             ll x=0,y=0;
49             if(mp[l[i]][r[i]]!=0){//去重 更改l[i]
50               ll now=l[i];
51               l[i]=mp[l[i]][r[i]];
52               mp[now][r[i]]=i+1;
53              }
54              else
55             mp[l[i]][r[i]]=i+1;
56             for(int j=i-1; j>=l[i]; j--)
57             {
58                 if((a[j]-a[i])<=k)
59                     x++;
60                 else
61                     break;
62             }
63             for(int j=i+1; j<=r[i]; j++)
64             {
65                 if((a[j]-a[i])<=k)
66                     y++;
67                 else
68                     break;
69             }
70             ans=ans+x*y+x+y+1ll;
71         }
72         printf("%lld\n",ans);
73     return 0;
74 }