洛谷 P1878 舞蹈课

Posted 2020-10-05 Alex丶Baker

P1878 舞蹈课

小根堆

 1 #include<bits/stdc++.h>
 2 #define ll long long
 3 #define maxn 200005
 4 #define inf 1<<30
 5 using namespace std;
 6 struct data{
 7     int w,pos;    
 8 };
 9 bool operator > (data a,data b){ return a.w>b.w||(a.w==b.w&&a.pos>b.pos); }
10 int n,ans;
11 int a[maxn],nxt[maxn],pre[maxn],a1[maxn],a2[maxn];
12 char ch[maxn];
13 bool if_[maxn];
14 priority_queue<data,vector<data>,greater<data> >q;
15 inline int read()
16 {
17     int x=0,f=1;char ch=getchar();
18     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
19     while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
20     return x*f;
21 }
22 
23 int main()
24 {
25     n=read(); if_[0]=1;
26     scanf("%s",ch+1);
27     for(int i=1;i<=n;i++) a[i]=read();
28     for(int i=1;i<n;i++) nxt[i]=i+1;
29     for(int i=2;i<=n;i++) pre[i]=i-1;
30     for(int i=1;i<n;i++)
31         if(ch[i]!=ch[i+1])
32             q.push((data){abs(a[i]-a[i+1]),i});
33     while(!q.empty())
34     {
35         int mn=q.top().w,now=q.top().pos; q.pop();
36         int l=pre[now],t=nxt[now],r=nxt[t];
37         if(if_[now]||if_[t]) continue;
38         if(abs(a[now]-a[t])!=mn||ch[now]==ch[t]) continue;
39         if_[now]=if_[t]=1;
40         a1[++ans]=now; a2[ans]=t;
41         if(l&&r&&ch[r]!=ch[l]) q.push((data){abs(a[r]-a[l]),l});
42         nxt[l]=r; pre[r]=l;
43     }
44     printf("%d\n",ans);
45     for(int i=1;i<=ans;i++)
46         printf("%d %d\n",a1[i],a2[i]);
47     return 0;
48 }