每日编程-20170308-2

题目：给出两个自然数N和n，找到一组连续的自然数，其长度大于等于n，其和等于N。

输入：N（空格）n

输出：自然数列，每个数之间有空格，最后一个数后无空格 | 没有答案则输出：No answer

解答：

 1 #include <iostream>
 2 #include <vector>
 3 using std::cout; using std::endl; using std::cin;
 4 using std::vector;
 5
 6 int main() {
 7
 8     int N, n, sum = 0;　　//sum为总和
 9     vector<int> answer;　　//答案以vector形式保存,因为不确定会有多少
10     cin >> N >> n;　　//输入参数
11     for (auto i = 1; i <= N/2; i++)　　//遍历1到N/2，考虑到(N/2)+(N/2)+1 > N
12     {
13         for (auto j = i; sum < N ; j++)　　//从i开始遍历，直到数列和不小于N
14         {
15             sum += j;
16             answer.push_back(j);
17         }
18         if (sum == N && ((answer.end() - answer.begin()) > n))　　//如果sum等于N，并且answer长度大于n
19         {
20             for (auto beg = answer.begin(); beg != answer.end();beg++)　　//输出answer
21             {
22                 cout << *beg;
23                 if (beg+1 != answer.end())
24                 {
25                     cout << " ";
26                 }
27             }
28             break;
29         }
30         else　　//如果sum不等于N或者answer长度小于等于n
31         {
32             answer = {};　　//清空答案，sum清零
33             sum = 0;
34         }
35     }
36     if (answer.begin() == answer.end())　　//如果answer为空，没有答案
37     {
38         cout << "No answer" << endl;
39     }
40 }

第二版

 1 #include <iostream>
 2 #include <vector>
 3 using std::cout; using std::endl; using std::cin;
 4 using std::vector;
 5
 6 int main() {
 7
 8     int N, n, sum = 0;
 9     vector<int> answer;
10     cin >> N >> n;
11     for (auto i = 1; i <= N/n; i++)　　//数学改进，n(N/n) + n-1 > n
12     {
13         for (auto j = i; sum < N ; j++)
14         {
15             sum += j;
16             answer.push_back(j);
17         }
18         if (sum == N && (answer.size() > n)) 　　//刚才脑残了，把size忘了
19         {
20             for (auto beg = answer.begin(); beg != answer.end();beg++)
21             {
22                 cout << *beg;
23                 if (beg+1 != answer.end())
24                 {
25                     cout << " ";
26                 }
27             }
28             break;
29         }
30         else
31         {
32             answer = {};
33             sum = 0;
34         }
35     }
36     if (answer.begin() == answer.end())
37     {
38         cout << "No answer" << endl;
39     }
40 }