Can you answer these queries I
Time Limit: 1000ms
Memory Limit: 262144KB
This problem will be judged on SPOJ. Original ID: GSS164-bit integer IO format: %lld Java class name: Main
You are given a sequence $A[1], A[2], ..., A[N] $. $( |A[i]| leq 15007 , 1leq N leq 50000 )$. A query is defined as follows:
$Query(x,y) = Max { a[i]+a[i+1]+...+a[j] ; x leq i leq j leq y }$.
Given M queries, your program must output the results of these queries.
Input
-
The first line of the input file contains the integer N.
-
In the second line, N numbers follow.
-
The third line contains the integer M.
-
M lines follow, where line i contains 2 numbers xi and yi.
Output
- Your program should output the results of the M queries, one query per line.
Example
Input: 3 -1 2 3 1 1 2 Output: 2
解题：线段树
1 #include <bits/stdc++.h> 2 using namespace std; 3 const int maxn = 50010; 4 struct node{ 5 int lt,rt,lsum,rsum,sum,msum; 6 }tree[maxn<<2]; 7 inline void pushup(int v){ 8 tree[v].sum = tree[v<<1].sum + tree[v<<1|1].sum; 9 tree[v].lsum = max(tree[v<<1].lsum,tree[v<<1].sum + tree[v<<1|1].lsum); 10 tree[v].rsum = max(tree[v<<1|1].rsum,tree[v<<1|1].sum + tree[v<<1].rsum); 11 tree[v].msum = max(max(tree[v<<1].msum,tree[v<<1|1].msum),tree[v<<1].rsum + tree[v<<1|1].lsum); 12 } 13 void build(int lt,int rt,int v){ 14 tree[v].lt = lt; 15 tree[v].rt = rt; 16 if(lt == rt){ 17 scanf("%d",&tree[v].sum); 18 tree[v].msum = tree[v].lsum = tree[v].rsum = tree[v].sum; 19 return; 20 } 21 int mid = (lt + rt)>>1; 22 build(lt,mid,v<<1); 23 build(mid + 1,rt,v<<1|1); 24 pushup(v); 25 } 26 node query(int lt,int rt,int v){ 27 if(lt <= tree[v].lt && rt >= tree[v].rt) return tree[v]; 28 int mid = (tree[v].lt + tree[v].rt)>>1; 29 if(rt <= mid) return query(lt,rt,v<<1); 30 if(lt > mid) return query(lt,rt,v<<1|1); 31 node a = query(lt,rt,v<<1); 32 node b = query(lt,rt,v<<1|1); 33 node c; 34 c.sum = a.sum + b.sum; 35 c.lsum = max(a.lsum,a.sum + b.lsum); 36 c.rsum = max(b.rsum,b.sum + a.rsum); 37 c.msum = max(max(a.msum,b.msum),a.rsum + b.lsum); 38 return c; 39 } 40 int main(){ 41 int n,m,x,y; 42 while(~scanf("%d",&n)){ 43 build(1,n,1); 44 scanf("%d",&m); 45 while(m--){ 46 scanf("%d%d",&x,&y); 47 node d = query(x,y,1); 48 printf("%d ",max(max(d.sum,d.msum),max(d.lsum,d.rsum))); 49 } 50 } 51 return 0; 52 }