HDU 1003 最大连续字数段问题

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

  
   3
5 6 -1 5 4 -7
7 0 6 -1 1 -6 7 -5
  
  
   13 1 2 3 -100 1 2 3 -100 1 2 1 1 1

Sample Output

  
   Case 1:
14 1 4

Case 2:
7 1 6
  
  
   Case 3：
  
  
   6 1 3
  
  

  
  
   这个题要注意一句：如果有相等的，输出最靠前的一个
  
  
   这个是正确的代码：
  
  
   #include <stdio.h>
#include <iostream>
using namespace std;
int a[100005];
int main()
{
    int t;
    cin >> t;
    for(int j=1;j<=t;j++)
    {
        int n;
        cin >> n;
        for(int i=0;i<n;i++)
        {
            cin >> a[i];
        }
        int x=0;//必须初始化，防止全是负数的数据
        int y=0;
        int start=0;
        int end=0;
        int max=a[0];
        int sum=a[0];
        for(int i=1;i<n;i++)
        {
            if(sum<0)
            {
                sum=a[i];
                x=y=i;
            }
            else
            {
              sum+=a[i];
              y++;
            }
            if(sum>max)
            {
                max=sum;
                start=x;
                end=y;
            }
        }
        cout << "Case "<<j<<":\n";
        if(j==t)
          cout << max<<" "<<start+1 << " "<< end+1 <<endl;
        else
          cout << max<<" "<<start+1 << " "<< end+1 <<endl << endl;
    }
    return 0;
}

   
如果没有这句话，代码可以写为：
  
  
   #include <stdio.h>
#include <iostream>
using namespace std;
int a[100005];
int main()
{
    int t;
    cin >> t;
    for(int j=1;j<=t;j++)
    {
        int n;
        cin >> n;
        for(int i=0;i<n;i++)
        {
            cin >> a[i];
        }
        int start=0;
        int end=0;
        int max=a[0];
        int sum=a[0];
        for(int i=1;i<n;i++)
        {
            if(sum<0)
            {
                start=i;
                sum=0;
            }
            sum+=a[i];
            if(sum>=max)
            {
                max=sum;
                end=i;
               // cout << end << endl;
            }
        }
        cout << "Case"<<" "<<j<<":\n";
        if(j==t)
          cout << max<<" "<<start+1 << " "<< end+1 <<endl;
        else
          cout << max<<" "<<start+1 << " "<< end+1 <<endl << endl;
    }
    return 0;
}

原文链接：https://blog.csdn.net/u013573047/article/details/19283085