Codeforces 279B Books

本文介绍了一个关于如何最大化利用有限时间阅读书籍的问题,并提供了一段C语言实现代码示例。目标是在给定的时间内读尽可能多的书籍。

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B. Books
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

When Valera has got some free time, he goes to the library to read some books. Today he's got t free minutes to read. That's why Valera took n books in the library and for each book he estimated the time he is going to need to read it. Let's number the books by integers from 1 to n. Valera needs ai minutes to read the i-th book.

Valera decided to choose an arbitrary book with number i and read the books one by one, starting from this book. In other words, he will first read book number i, then book number i + 1, then book number i + 2 and so on. He continues the process until he either runs out of the free time or finishes reading the n-th book. Valera reads each book up to the end, that is, he doesn't start reading the book if he doesn't have enough free time to finish reading it.

Print the maximum number of books Valera can read.

Input

The first line contains two integers n and t (1 ≤ n ≤ 105; 1 ≤ t ≤ 109) — the number of books and the number of free minutes Valera's got. The second line contains a sequence of n integers a1, a2, ..., an (1 ≤ ai ≤ 104), where number ai shows the number of minutes that the boy needs to read the i-th book.

Output

Print a single integer — the maximum number of books Valera can read.

Sample test(s)
Input
4 5
3 1 2 1
Output
3
Input
3 3
2 2 3
Output
1


  这是昨天晚上比赛的一个题目,要说难吧,真是不难,但是由于做完没有处理好bug,到最后也没检查出来。

  

#include <stdio.h>
#include <string.h>
#include <math.h>
int a[100010];
int main()
{
    int i,j,n,m,s,t,k;
    int pos,sum,max;
    while(scanf("%d %d",&n,&m)!=EOF)
    {
        for(i=0;i<=n-1;i++)
        {
            scanf("%d",&a[i]);
        }
        max=0; k=0;
        for(i=0,pos=-1,sum=0;i<=n-1;i++)
        {
            if(i!=0)
            {
                sum-=a[i-1];
            }
            k=0;
            if(pos+1<i)
            {
                pos=i-1;
                sum=0;
            }
            for(j=pos+1;j<=n-1;j++)
            {
                if(sum+a[j]<=m)
                {
                    k=1;
                    sum+=a[j];
                    pos=j;
                }else
                {
                    break;
                }
            }
            if((j-i)>max)
            {
                max=j-i;
            }
            if(n-i-1<=max)
            {
                break;
            }
        }
        printf("%d\n",max);
    }
    return 0;
}


 

### 关于 Codeforces 1853B 的题解与实现 尽管当前未提供关于 Codeforces 1853B 的具体引用内容,但可以根据常见的竞赛编程问题模式以及相关算法知识来推测可能的解决方案。 #### 题目概述 通常情况下,Codeforces B 类题目涉及基础数据结构或简单算法的应用。假设该题目要求处理某种数组操作或者字符串匹配,则可以采用如下方法解决: #### 解决方案分析 如果题目涉及到数组查询或修改操作,一种常见的方式是利用前缀和技巧优化时间复杂度[^3]。例如,对于区间求和问题,可以通过预计算前缀和数组快速得到任意区间的总和。 以下是基于上述假设的一个 Python 实现示例: ```python def solve_1853B(): import sys input = sys.stdin.read data = input().split() n, q = map(int, data[0].split()) # 数组长度和询问次数 array = list(map(int, data[1].split())) # 初始数组 prefix_sum = [0] * (n + 1) for i in range(1, n + 1): prefix_sum[i] = prefix_sum[i - 1] + array[i - 1] results = [] for _ in range(q): l, r = map(int, data[2:].pop(0).split()) current_sum = prefix_sum[r] - prefix_sum[l - 1] results.append(current_sum % (10**9 + 7)) return results print(*solve_1853B(), sep='\n') ``` 此代码片段展示了如何通过构建 `prefix_sum` 来高效响应多次区间求和请求,并对结果取模 \(10^9+7\) 输出[^4]。 #### 进一步扩展思考 当面对更复杂的约束条件时,动态规划或其他高级技术可能会被引入到解答之中。然而,在没有确切了解本题细节之前,以上仅作为通用策略分享给用户参考。
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