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Subvetor de soma máxima - Paradigmas

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/*
 * Largest subvector sum
 *
 * Author: Howard Cheng
 * Reference: Programming Pearl, page 74
 *
 * Given an array of integers, we find the continguous subvector that
 * gives the maximum sum.  If all entries are negative, it returns
 * an empty vector with sum = 0.
 *
 * If we want the subvector to be nonempty, we should first scan for the
 * largest element in the vector (1-element subvector) and combine the
 * result in this routine.
 *
 * The sum is returned, as well as the start and the end position
 * (inclusive).  If start > end, then the subvector is empty.
 *
 */

#include 
#include 
#include 

int vecsum(int *v, int n, int *start, int *end)
{
  int maxval = 0;
  int max_end = 0;
  int max_end_start, max_end_end;
  int i;

  *start = max_end_start = 0;
  *end = max_end_end = -1;
  for (i = 0; i < n; i++) {
    if (v[i] + max_end >= 0) {
      max_end = v[i] + max_end;
      max_end_end = i;
    } else {
      max_end_start = i+1;
      max_end_end = -1;
      max_end = 0;
    }

    if (maxval < max_end) {
      *start = max_end_start;
      *end = max_end_end;
      maxval = max_end;
    } else if (maxval == max_end) {
      /* put whatever preferences we have for a tie */
      /* eg. longest subvector, and then the one that starts the earliest */
      if (max_end_end - max_end_start > *end - *start ||
          (max_end_end - max_end_start == *end - *start &&
           max_end_start < *start)) {
        *start = max_end_start;
        *end = max_end_end;
        maxval = max_end;
      }
    }
  }
  return maxval;
}

int main(void)
{
  int n;
  int *v;
  int i;
  int sum, start, end;

  while (scanf("%d", &n) == 1 && n > 0) {
    v = (int *)malloc(n*sizeof(int));
    assert(v);
    for (i = 0; i < n; i++) {
      scanf("%d", &(v[i]));
    }
    sum = vecsum(v, n, &start, &end);
    printf("Maximum sum %d from %d to %d.\n", sum, start, end);
    free(v);
  }

  return 0;
}
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