UESTC 1598 兰斯的后宫计划

这道题可以用线段树来求解，当然，如果给的数据没有负值，同样可以用二分的思想去做，效率和线段树差不多

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 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<string.h>
 4 #define max(a,b) a>b?a:b
 5 struct node
 6 {
 7     int left,right,maxSum;
 8 };
 9 node Tree[400100];
10 int sum[100010],value[100010];
11 void build_tree(int k,int left,int right)
12 {
13     Tree[k].left=left;
14     Tree[k].right=right;
15     if(left==right)
16     {
17         Tree[k].maxSum=sum[left];
18         return ;
19     }
20     int mid=(left+right)>>1;
21     build_tree(k<<1,left,mid);
22     build_tree((k<<1)+1,mid+1,right);
23     Tree[k].maxSum=max(Tree[k<<1].maxSum,Tree[(k<<1)+1].maxSum);    
24 }
25 int findMinIndex(int k,int val)
26 {
27     if(Tree[k].left==Tree[k].right)return Tree[k].left;
28     if(Tree[k<<1].maxSum>=val)return findMinIndex(k<<1,val);
29     else return findMinIndex(2*k+1,val);
30 }
31 int main(void)
32 {
33     int T,n,m,i,j;
34     scanf("%d",&T);
35     while(T--)
36     {
37         scanf("%d %d",&n,&m);
38         sum[0]=0;
39         int ans=0;
40         for(i=1;i<=n;i++)
41         {
42             scanf("%d",&value[i]);
43             sum[i]=sum[i-1]+value[i];
44         }
45         build_tree(1,0,n);
46         for(i=1;i<=n;i++)
47         {
48             int temp=findMinIndex(1,sum[i]-m);
49             ans=max(ans,i-temp);
50         }
51         printf("%d\n",ans);
52     }
53 }