最大子序列和

      #include <stdio.h>
#include <stdlib.h>

int main()
{
	int this_sum, max_sum, old_first, old_last, new_first;
	int n,i, tmp, flag = 1;
	int first = 1;
	int *data;
	
	scanf("%d", &n);
	this_sum= max_sum = old_first = new_first = 0;
	old_last = n - 1;
		
	data = (int *)malloc(n * sizeof(int));
    for(i = 0; i < n; i ++)
    {
        scanf("%d", &data[i]);
    }
	
	for(i = 0; i < n; i++)
	{
		this_sum += data[i];/*向右累加*/
		if(first)//第一次找到最大的和
		{
			if(this_sum >= 0)
			{
				first = 0;
				old_first = old_last = i;
						
			}	
		}	
		if(flag)//获取新的this_sum的开头
		{
			if(this_sum >= 0)
			{
				flag = 0;
				new_first = i;	
			}	
		}
		if(this_sum > max_sum)
		{
			max_sum = this_sum;/*发现更大的和，则更新当前结果*/ 
			old_last = i;
			if(new_first != old_first)
			{
				old_first = new_first;
			}	
		}
		else if(this_sum < 0)/*假设当前子序列和为负*/ 
		{
			this_sum = 0;/*则不可能使后面的和增大，抛弃之*/	
			flag = 1;
		}
	}	
	printf("%d %d %d\n", max_sum, data[old_first], data[old_last]);
	return 0;
}