the Sum of Cube

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 162    Accepted Submission(s): 101

Problem Description

A range is given, the begin and the end are both integers. You should sum the cube of all the integers in the range.

Input

The first line of the input is T(1 <= T <= 1000), which stands for the number of test cases you need to solve.
Each case of input is a pair of integer A,B(0 < A <= B <= 10000),representing the range[A,B].

Output

For
each test case, print a line “Case #t: ”(without quotes, t means the
index of the test case) at the beginning. Then output the answer – sum
the cube of all the integers in the range.

Sample Input

2
1 3
2 5

Sample Output

Case #1: 36
Case #2: 224

Source

2014 ACM/ICPC Asia Regional Shanghai Online

1^3+2^3+4^3.....+n^3=(n*(n+1)/2)^2

代码：

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cstdlib>
 5 using namespace std;
 6
 7 int main()
 8 {
 9   int cas;
10  __int64 a,b;
11  scanf("%d",&cas);
12  for(int i=1;i<=cas;i++)
13  {
14      scanf("%I64d%I64d",&a,&b);
15      printf("Case #%d: %I64d\n",i,(b*(b+1)/2)*(b*(b+1)/2)-(a*(a-1)/2)*(a*(a-1)/2));
16  }
17  return 0;
18 }