bzoj 4540: [Hnoi2016]序列
额，呵呵呵一脸懵逼
贴个题解吧：http://blog.csdn.net/thy_asdf/article/details/51203510
感觉做这样的题还是多想想莫队怎么搞，毕竟不强制在线。。
1 #include <bits/stdc++.h> 2 #define LL long long 3 using namespace std; 4 inline int ra() 5 { 6 int x=0,f=1; char ch=getchar(); 7 while (ch<'0' || ch>'9') {if (ch=='-') f=-1; ch=getchar();} 8 while (ch>='0' && ch<='9') {x=x*10+ch-'0'; ch=getchar();} 9 return x*f; 10 } 11 12 const int maxn=100005; 13 14 int n,T,block,top,a[maxn],st[maxn][20],pw[20],stk[maxn],L[maxn],R[maxn],belong[maxn],lg[maxn]; 15 LL sl[maxn],sr[maxn],now,ans[maxn]; 16 struct node{int l,r,id;}q[maxn]; 17 18 int MIN(int x, int y) {return a[x]<a[y]?x:y;} 19 void ST() 20 { 21 lg[0]=-1; pw[0]=1; 22 for (int i=1; i<=18; i++) pw[i]=pw[i-1]<<1; 23 for (int i=1; i<=n; i++) lg[i]=lg[i>>1]+1,belong[i]=(i-1)/block+1; 24 for (int i=1; i<=n; i++) st[i][0]=i; 25 for (int j=1; j<=18; j++) 26 for (int i=1; i<=n; i++) 27 { 28 st[i][j]=st[i][j-1]; 29 if (i+pw[j-1]<=n) st[i][j]=MIN(st[i][j-1],st[i+pw[j-1]][j-1]); 30 } 31 } 32 33 int cal(int l, int r) 34 { 35 if (l>r) swap(l,r); 36 int orz=lg[r-l+1]; 37 return MIN(st[l][orz],st[r-pw[orz]+1][orz]); 38 } 39 void change_L(int l, int r, int opt) 40 { 41 int p=cal(l,r); 42 LL tmp=(LL)a[p]*(r-p+1)+sr[l]-sr[p]; 43 now+=opt*tmp; 44 } 45 void change_R(int l, int r, int opt) 46 { 47 int p=cal(l,r); 48 LL tmp=(LL)a[p]*(p-l+1)+sl[r]-sl[p]; 49 now+=opt*tmp; 50 } 51 bool cmp(node a, node b) {return belong[a.l]<belong[b.l] || (belong[a.l]==belong[b.l] && a.r<b.r);} 52 void solve() 53 { 54 sort(q+1,q+T+1,cmp); now=a[1]; 55 for (int l=1,r=1,i=1; i<=T; i++) 56 { 57 while (r<q[i].r) change_R(l,++r,1); 58 while (l>q[i].l) change_L(--l,r,1); 59 while (r>q[i].r) change_R(l,r--,-1); 60 while (l<q[i].l) change_L(l++,r,-1); 61 ans[q[i].id]=now; 62 } 63 for (int i=1; i<=T; i++) printf("%lld\n",ans[i]); 64 } 65 int main(int argc, char const *argv[]) 66 { 67 n=ra(); T=ra(); block=sqrt(n); 68 for (int i=1; i<=n; i++) a[i]=ra(); 69 ST(); 70 for (int i=1; i<=n; i++) 71 { 72 while (top && a[stk[top]]>=a[i]) R[stk[top--]]=i; 73 stk[++top]=i; 74 } 75 while (top) R[stk[top--]]=n+1; 76 for (int i=n; i>=1; i--) 77 { 78 while (top && a[stk[top]]>a[i]) L[stk[top--]]=i; 79 stk[++top]=i; 80 } 81 while (top) L[stk[top--]]=0; 82 for (int i=n; i>=1; i--) sr[i]=sr[R[i]]+(LL)(R[i]-i)*a[i]; 83 for (int i=1; i<=n; i++) sl[i]=sl[L[i]]+(LL)(i-L[i])*a[i]; 84 for (int i=1; i<=T; i++) q[i].l=ra(),q[i].r=ra(),q[i].id=i; 85 solve(); 86 return 0; 87 }
