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)/*如果当前子序列和为负*/ 
{
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;
}