- Source:
- PAT A1104 Sum of Number Segments (20 分)
- Description:
- Given a sequence of positive numbers, a segment is defined to be a consecutive subsequence. For example, given the sequence {
- 0.1, 0.2, 0.3, 0.4
- }, we have 10 segments: (0.1) (0.1, 0.2) (0.1, 0.2, 0.3) (0.1, 0.2, 0.3, 0.4) (0.2) (0.2, 0.3) (0.2, 0.3, 0.4) (0.3) (0.3, 0.4) and (0.4).
- Now given a sequence, you are supposed to find the sum of all the numbers in all the segments. For the previous example, the sum of all the 10 segments is 0.1 + 0.3 + 0.6 + 1.0 + 0.2 + 0.5 + 0.9 + 0.3 + 0.7 + 0.4 = 5.0.
- Input Specification:
Each input file contains one test case. For each case, the first line gives a positive integer N, the size of the sequence which is no more than 1. The next line contains N positive numbers in the sequence, each no more than 1.0, separated by a space.
- Output Specification:
- For each test case, print in one line the sum of all the numbers in all the segments, accurate up to 2 decimal places.
- Sample Input:
- 4 0.1 0.2 0.3 0.4
- Sample Output:
- 5.00
- Key:
模拟题
Attention:
i*(n-i+1)*x,3 和 4 测试点会报错
- Code:
- #include<cstdio>
- int main()
- {
- #ifdef ONLINE_JUDGE
- #else
- freopen("Test.txt", "r", stdin);
- #endif // ONLINE_JUDGE
- int n;
- double x,sum=0;
- scanf("%d", &n);
- for(int i=1; i<=n; i++)
- {
- scanf("%lf", &x);
- sum += (x*i*(n-i+1));
- }
- printf("%.2f\n", sum);
- return 0;
- }
来源: http://www.bubuko.com/infodetail-3163619.html