迭代dfs算法产生sigkill错误

Question

用于迭代dfs算法的伪代码

Mark all unblocked positions in the maze as "UNVISITED"
   push the start position's coordinates on the stack
   mark the start position as “VISITED”
  While (stack is not empty and end has not been found)
    if the coordinate at the Top of the Stack is the end position
      then end has been found (break out of loop)
    if the coordinate at the Top of the Stack has an unvisited (and unblocked)       
neighbor
      push the coordinates of one unvisited neighbor on the stack
      mark that one unvisited neighbor as visited
    else
      pop the coordinate at the Top of the Stack
  If the stack is empty
      The maze has no solution
  else
      The items on the stack contain the coordinates of the solution from the end 
of the maze to the start of the maze. 

用于迭代dfs算法的C代码，可按值返回迷宫并按引用进行堆栈

maze DEPTH_FIRST_SEARCH(Stack *s, maze m1)
{
    int found = 0;
    //Mark all unblocked positions in the maze as "UNVISITED
    //push the start position's coordinates on the stack 
    int visited[m1.xsize+2][m1.ysize+2];
    for(int i = 0; i < m1.xsize+2;i++)
    {
        for (int j = 0; j < m1.ysize+2; j++){
            visited[i][j] = 0;
        }
    }
    printf("Start: x: %d y:%d", m1.xstart,m1.ystart );
    push(&s, m1.xstart,m1.ystart);
    //mark the start position as “VISITED”
    visited[m1.xstart][m1.ystart] = 1;
    //While (stack is not empty and end has not been found)
    while(found != 1)
    {
        struct Node* node = top(&s);
        printf("x: %d y:%d", node->xcoord,node->ycoord );
        //if the coordinate at the Top of the Stack is the end position
        if((node->xcoord == m1.xend) && (node->ycoord == m1.yend))
        {
            //then end has been found (break out of loop)
            found = 1;
            break;
        }
        //if the coordinate at the Top of the Stack has an unvisited (and unblocked) down neighbor
        else if(visited[(node->xcoord)-1][node->ycoord] = 0 && m1.arr[(node->xcoord)-1][node->ycoord] == '.')
        {
            //push the coordinates of one unvisited neighbor on the stack
            //mark that one unvisited neighbor as visited  
             printf("down" );
            push(&s,(((node->xcoord)-1)), node->ycoord );
           visited[(node->xcoord)-1][node->ycoord] = 1;
        }
        //if the coordinate at the Top of the Stack has an unvisited (and unblocked) up neighbor
        else if(visited[(node->xcoord)+1][node->ycoord] = 0 && m1.arr[(node->xcoord)+1][node->ycoord] == '.' )
        {
            //push the coordinates of one unvisited neighbor on the stack
            //mark that one unvisited neighbor as visited 
             printf("up" );
            push(&s,((node->xcoord)+1), node->ycoord);
            visited[(node->xcoord)+1][node->ycoord] = 1;
        }
        //if the coordinate at the Top of the Stack has an unvisited (and unblocked) right neighbor
         else if(visited[(node->xcoord)][node->ycoord+1] = 0 && m1.arr[(node->xcoord)][node->ycoord+1] == '.')
        {
            //push the coordinates of one unvisited neighbor on the stack
            //mark that one unvisited neighbor as visited  
            printf("Right" );
            push(&s,node->xcoord, ((node->ycoord)+1 ));
            visited[(node->xcoord)][node->ycoord+1] = 1;
        }
        //if the coordinate at the Top of the Stack has an unvisited (and unblocked) left neighbor
        else if(visited[(node->xcoord)][node->ycoord-1] = 0 && m1.arr[(node->xcoord)-1][node->ycoord-1] == '.')
        {
            //push the coordinates of one unvisited neighbor on the stack
            //mark that one unvisited neighbor as visited 
            printf("left" );
            push(&s,node->xcoord, ((node->ycoord)-1) );
            visited[(node->xcoord)][node->ycoord-1] = 1;
        }
        else if(is_empty(s)==1)
        {
            break;
        }
        else
        {
            pop(&s);
        }

    }
    return m1;
}

内部main

int main (int argc, char **argv)
{
  maze m1;
  Stack *s;
  //commandline arg checker
  //debug checker
  //take in file mazedata
  //print out maze m1
  m1 = DEPTH_FIRST_SEARCH(&s, m1);
  //print out maze m1 after the dfs
}

输入     ./a.out mazedata1.txt 输出

size: 10, 20
start: 1, 1
end: 10, 20
**********************
*s........*..........*
*........*...........*
*..*....*............*
*.*....*.............*
**....*..............*
*....*...............*
*...*................*
*..*.................*
*....................*
*...................e*
**********************

我搜索了迭代dfs算法以在线解决迷宫问题，但是我只找到了用于求解图形和树的递归dfs算法就找不到任何东西。我的输出仅在dfs函数之前打印出迷宫，然后在dfs函数中停止工作，并且在函数之后不显示迷宫。我不知道是否需要包括堆栈函数和节点结构。感谢您的帮助。