DP求数列的最大和

HDOJ原题：

Problem Description

　　Given a sequence a[1],a[2],a[3]......a[n], your job is to calculate the max sum of a sub-sequence.
　　For example, given (6,-1,5,4,-7), the max sum in this sequence is 6 + (-1) + 5 + 4 = 14.

Input

　　The first line of the input contains an integer T(1<=T<=20) which means the number of test cases.
　　Then T lines follow, each line starts with a number N(1<=N<=100000), then N integers followed
　　(all the integers are between -1000 and 1000).

Output

　　For each test case, you should output two lines. The first line is "Case #:", # means the number of
　　the test case. The second line contains three integers, the Max Sum in the sequence, the
 　　start position of the sub-sequence, the end position of the sub-sequence. If there are
　　more than one result, output the first one. Output a blank line between two cases.

Sample Input

　　2 5 6 -1 5 4 -7 7 0 6 -1 1 -6 7 -5

Sample Output

　　Case 1: 14 1 4 Case 2: 7 1 6

 

 链接：http://acm.hdu.edu.cn/showproblem.php?pid=1003

 

C++程序如下：

# include <iostream>
using namespace std ;

int main()
{
   int line ;
   if (!(cin >> line)) return 0 ;
   for (int index = 1; index <= line; index++)
   {
      unsigned int n, i = 0 ;
      int sum = 0, max = -1001, temp = 1, first = 0, last = 0 ;
      if (!(cin >> n)) return 0 ;

      for (i = 0; i < n; i++)
      {
         int num ;
         if (cin >> num)
         {
            sum += num ;
            if (sum > max) { max = sum ; first = temp ; last = i + 1 ;}
            if (sum < 0) { sum = 0; temp = i + 2 ;}
         }
      }
      cout << "Case " << index << ":" << endl ;
      cout << max << " " << first << " " << last ;
      if (index == line) cout << endl ;
      else cout << endl << endl ;
   }
   return 0 ;
}