Cải thiện bài viết
Lưu bài viết
Đưa ra một số N. Nhiệm vụ là tìm tổng của chuỗi dưới đây cho đến kỳ thứ n. & Nbsp;
1- 2 + 3- 4 + 5- 6 +.
Examples: :
Input : N = 8 Output : -4 Input : N = 10001 Output : 5001
Cách tiếp cận: Nếu chúng ta quan sát cẩn thận, chúng ta có thể thấy rằng tổng của chuỗi trên theo mô hình các số nguyên dương và âm xen kẽ bắt đầu từ 1 đến N như hình dưới đây: & nbsp; If we observe carefully, we can see that the sum of the above series follows a pattern of alternating positive and negative
integers starting from 1 to N as shown below:
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......
Do đó, từ mẫu trên, chúng ta có thể kết luận rằng: & nbsp; & nbsp;
- Khi n là lẻ => sum = [n+1]/2
- Khi n chẵn => sum = [-1]*n/2
Dưới đây là việc thực hiện phương pháp trên: & nbsp;
C++
#include
using
namespace
std;
int
solve_sum[
int
n]
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......0
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......2
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......3
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......4
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......6
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......9
#include
0
int
#include
2
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......0
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
int
#include
6N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
#include
8N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
using
1#include
0
Java
using
3 using
4
using
5 using
6
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......0
using
8 int
namespace
0int
n]
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......0
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......2
namespace
6namespace
7 namespace
8namespace
9std;
0N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......4
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
std;
3namespace
9std;
5namespace
7std;
7N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
int
0namespace
7std;
7#include
0
int
4 using
8 int
6 int
7
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......0
int
solve_sum[
0solve_sum[
1std;
7
solve_sum[
3
#include
0
#include
0
Python 3
solve_sum[
6 solve_sum[
7
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......2
int
0int
1 namespace
7 int
3int
3N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......4
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
int
0n]
0 namespace
9std;
0using
namespace
7N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
n]
7n]
8n]
3 namespace
7n]
8int
3 solve_sum[
1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......04
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......05
int
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......07
C#
using
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......09
using
5 using
6
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......0
using
8 int
namespace
0int
n]
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......0
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......2
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......3
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......4
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......6
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......9
#include
0
int
#include
2
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......0
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
int
#include
6N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......38
#include
0
#include
0
N = 1, 2, 3, 4, 5, 6, 7 ......
Sum = 1, -1, 2, -2, 3, -3, 4 ......
1N = 1, 2, 3, 4, 5, 6, 7 ......
Sum = 1, -1, 2, -2, 3, -3, 4 ......
5 using
1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......41
Java
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......0
using
3 using
4
using
5 using
6
using
8 int
namespace
0int
n]
#include
0
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......2
namespace
6namespace
7 namespace
8namespace
9std;
0N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......4
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
std;
3namespace
9std;
5namespace
7std;
7N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......69
N = 1, 2, 3, 4, 5, 6, 7 ......
Sum = 1, -1, 2, -2, 3, -3, 4 ......
1N = 1, 2, 3, 4, 5, 6, 7 ......
Sum = 1, -1, 2, -2, 3, -3, 4 ......
5 int
0namespace
7std;
7
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......70
int
4 using
8 int
6 int
7
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......0
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......2
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......3
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......4
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......6
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......1
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......5
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......9
#include
0
int
#include
2
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......86
N = 1, 2, 3, 4, 5, 6, 7 ...... Sum = 1, -1, 2, -2, 3, -3, 4 ......87
N = 1, 2, 3, 4, 5, 6, 7 ......
Sum = 1, -1, 2, -2, 3, -3, 4 ......
1int
#include
6 O[1]
N = 1, 2, 3, 4, 5, 6, 7 ......
Sum = 1, -1, 2, -2, 3, -3, 4 ......
1N = 1, 2, 3, 4, 5, 6, 7 ......
Sum = 1, -1, 2, -2, 3, -3, 4 ......
5 using
1O[1] , since no extra space has been taken.