vector<int> time(n);
时间: 2023-09-23 12:04:19 浏览: 33
这行代码定义了一个名为 `time` 的 `vector` 对象,其中 `vector<int>` 表示这是一个存储整数类型的 `vector` 对象。`n` 是一个变量或者常量,表示这个 `vector` 对象的长度,即它可以存储的整数个数。这个 `vector` 对象中的每一个元素都可以通过下标来访问和修改,例如 `time[0]` 表示访问第一个元素,`time[1]` 表示访问第二个元素,以此类推。在这个定义中,`time` 初始化为一个长度为 `n` 的空 `vector` 对象,即其中没有任何元素。如果需要给 `time` 中的元素赋值,可以使用如下方式:
```cpp
time[0] = 1; // 给第一个元素赋值为1
time[1] = 2; // 给第二个元素赋值为2
// ...
```
也可以使用 `push_back` 函数向 `vector` 中添加元素,例如:
```cpp
time.push_back(1); // 向末尾添加一个元素1
time.push_back(2); // 再向末尾添加一个元素2
// ...
```
这样,`vector` 对象中的元素个数会动态增加,不需要提前指定长度。
相关问题
Joseph question: n knight numbers 1, 2, n. Sitting around the round table. Knights numbered 1 start counting from 1, those who report to m are listed, and then the next position starts counting from 1 to find the last knight number left next to the round table. (1) Write a function template. Using a type of sequential container as a template parameter, solve the Joseph problem using a specified type of sequential container in the template. m. N is the formal parameter of the function template. (2) Call the function template with vector<int>, deque<int>, and list<int>as type parameters. When calling, set n to a larger number and m to a smaller number (such as n=100000, n=5). Observe the time it takes to call the function template in three scenarios. Note: To submit the answer to this question, only one sequential container type needs to be selected as the template parameter. [Input Form] Input for program reference (prompt text before numbers): Input n and m:7 3 Output Form Output of program reference: Result:4 Sample Input Input n and m:7 3 Sample output Result:4 Sample Description Scoring criteria #include<iostream> #include<vector> using namespace std; int main() { vector<int> a; int n,m,x=0; cout<<"Input n and m:"; cin>>n>>m; a.resize(n); for(int i=0;i<n;i++) { a[i]=i+1; } cout<<"Result:"<<a[0]<<endl; return 0; }
Here's the function template to solve the Joseph problem using a specified type of sequential container as the template parameter:
```cpp
template<typename Container>
int joseph(int n, int m) {
Container knights;
for (int i = 1; i <= n; ++i) {
knights.push_back(i);
}
auto it = knights.begin();
while (knights.size() > 1) {
for (int i = 1; i < m; ++i) {
++it;
if (it == knights.end()) {
it = knights.begin();
}
}
it = knights.erase(it);
if (it == knights.end()) {
it = knights.begin();
}
}
return knights.front();
}
```
The function takes two integer parameters `n` and `m`, which are the number of knights and the count to skip before removing a knight, respectively. The function returns the number of the last knight left standing.
To call the function with different sequential container types, we can use the following code:
```cpp
int main() {
int n = 100000;
int m = 5;
// Using vector<int>
auto start_time = chrono::steady_clock::now();
int result = joseph<vector<int>>(n, m);
auto end_time = chrono::steady_clock::now();
cout << "vector<int>: " << result << ", time: " << chrono::duration_cast<chrono::milliseconds>(end_time - start_time).count() << "ms" << endl;
// Using deque<int>
start_time = chrono::steady_clock::now();
result = joseph<deque<int>>(n, m);
end_time = chrono::steady_clock::now();
cout << "deque<int>: " << result << ", time: " << chrono::duration_cast<chrono::milliseconds>(end_time - start_time).count() << "ms" << endl;
// Using list<int>
start_time = chrono::steady_clock::now();
result = joseph<list<int>>(n, m);
end_time = chrono::steady_clock::now();
cout << "list<int>: " << result << ", time: " << chrono::duration_cast<chrono::milliseconds>(end_time - start_time).count() << "ms" << endl;
return 0;
}
```
This code first sets `n` and `m` to the desired values. It then calls the `joseph` function with `vector<int>`, `deque<int>`, and `list<int>` as the sequential container types, and measures the time it takes to run each call using the `chrono` library. Finally, it prints the results and the execution times for each container type.
Note that the time it takes to run the function depends on the size of `n` and the value of `m`. For large values of `n` and small values of `m`, the function may take a long time to run, especially for `list<int>` which has slower insertions and deletions than `vector<int>` and `deque<int>`.
约瑟夫问题:n个骑士编号1,2,...,n,围坐在圆桌旁。编号为1的骑士从1开始报数,报到m的骑士出列,然后下一个位置再从1开始报数,找出最后留在圆桌旁的骑士编号。 (1)编写一个函数模板。以一种顺序容器的类型作为模板参数,在模板中使用指定类型的顺序容器求解约瑟夫问题。m,n是该函数模板的形参。 (2)分别以vector<int>,deque<int>,list<int>作为类型参数调用该函数模板,调用时将n设为较大的数,将m设为较小的数(例如令n=100000,n=5)。观察3种情况下调用该函数模板所需花费的时间。 注:本题答案的提交只需选择一种顺序容器类型作为模板参数。 【输入形式】 程序参考的输入(数字前为提示文字): Input n and m:7 3 【输出形式】 程序参考的输出: Result:4 【样例输入】 Input n and m:7 3 【样例输出】 Result:4 【样例说明】 【评分标准】 #include<iostream> #include<vector> using namespace std; int main() { vector<int> a; int n,m,x=0; cout<<"Input n and m:"; cin>>n>>m; a.resize(n); for(int i=0;i<n;i++) { a[i]=i+1; } cout<<"Result:"<<a[0]<<endl; return 0; }
```cpp
#include<iostream>
#include<vector>
#include<deque>
#include<list>
#include<chrono> // 用于计时
using namespace std;
// 定义函数模板
template<typename Container>
int josephus(int n, int m) {
Container knights(n); // 创建容器并初始化
for(int i = 0; i < n; i++) {
knights[i] = i + 1;
}
int pos = 0; // 初始位置为0
while(n > 1) {
pos = (pos + m - 1) % n; // 计算出列位置
knights.erase(knights.begin() + pos); // 移除骑士
n--; // 骑士数减1
}
return knights[0]; // 返回最后剩余的骑士编号
}
int main() {
int n, m;
cout << "Input n and m: ";
cin >> n >> m;
// 使用vector容器
auto start = chrono::steady_clock::now(); // 记录开始时间
int result = josephus<vector<int>>(n, m);
auto end = chrono::steady_clock::now(); // 记录结束时间
cout << "Using vector: " << result << endl;
cout << "Time cost: " << chrono::duration_cast<chrono::microseconds>(end - start).count() << " us" << endl;
// 使用deque容器
start = chrono::steady_clock::now();
result = josephus<deque<int>>(n, m);
end = chrono::steady_clock::now();
cout << "Using deque: " << result << endl;
cout << "Time cost: " << chrono::duration_cast<chrono::microseconds>(end - start).count() << " us" << endl;
// 使用list容器
start = chrono::steady_clock::now();
result = josephus<list<int>>(n, m);
end = chrono::steady_clock::now();
cout << "Using list: " << result << endl;
cout << "Time cost: " << chrono::duration_cast<chrono::microseconds>(end - start).count() << " us" << endl;
return 0;
}
```