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#include "cs.h"
/* depth-first search and postorder of a tree rooted at node j */
int cs_tdfs (int j, int k, int *head, const int *next, int *post, int *stack)
{
int i, p, top = 0 ;
if (!head || !next || !post || !stack) return (-1) ; /* check inputs */
stack [0] = j ; /* place j on the stack */
while (top >= 0) /* while (stack is not empty) */
{
p = stack [top] ; /* p = top of stack */
i = head [p] ; /* i = youngest child of p */
if (i == -1)
{
top-- ; /* p has no unordered children left */
post [k++] = p ; /* node p is the kth postordered node */
}
else
{
head [p] = next [i] ; /* remove i from children of p */
stack [++top] = i ; /* start dfs on child node i */
}
}
return (k) ;
}
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