Stack栈——getMin()

获取栈——stack中最小的元素

1. 建立另一个栈——temp
2. 如果两个栈都为空，则将node同时push两个栈中
3. 接着插入new_node，如果temp不为空，则比较栈顶node->data和new_node->data。
4. 如果node->data大于new_node->data，则将new_node同时push两个栈中
5. 反之，只push进stack栈中

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

struct stack
{
    int data;
    struct stack * next;
};
struct stack * newNode(int data)
{
    struct stack * new_node = (struct stack *)malloc(sizeof(struct stack));
    new_node->data = data;
    new_node->next = NULL;
}
void push(struct stack ** root, int data)
{
    struct stack * new_node = newNode(data);

    new_node->next = (*root);
    (*root) = new_node;
    printf("
%-2d pushed to stack", data);
}
int isEmpty(struct stack * root)
{
    return NULL == root ? 1 : 0;
}
int pop(struct stack ** root)
{
    if(isEmpty((*root)))
    {
        printf("
Empty!");
        return 0;
    }
    struct stack * temp = (*root);
    int num = temp->data;
    (*root) = temp->next;
    free(temp);

    return num;
}
void push_new(struct stack ** root, struct stack ** other, int data)
{
    if(NULL == (*root) || NULL == (*other))
    {
        push(root, data);
        push(other, data);
    }
    else if(data < ((*other)->data))
    {
        printf("
%-2d poped off", pop(other));
        push(other, data);
        push(root, data);
    }else if(data > ((*other)->data))
    {
        push(root, data);
    }
}
int getMin(struct stack * other)
{
    return other->data;
}
int main(void)
{
    struct stack * root = NULL;
    struct stack * other = NULL;

    push_new(&root, &other, -5);
    push_new(&root, &other, 1);
    push_new(&root, &other, 8);
    push_new(&root, &other, 0);
    push_new(&root, &other, -1);
    push_new(&root, &other, -7);

    printf("
MIN = %d", getMin(other));
    return 0;
}