leetcode155-最小栈

Posted 2021-01-24 xinfenglee

typedef struct {
    int *top;
    int *base;
    int statckSize;
    
} MinStack;

/** initialize your data structure here. */
MinStack* minStackCreate(int maxSize) {
    MinStack *stack = (MinStack*)malloc(sizeof(MinStack));
    stack->base = (int*)malloc(maxSize*sizeof(int));
    stack->top = stack->base;
    stack->statckSize = maxSize;
    return stack;
}

void minStackPush(MinStack* obj, int x) {
    if(obj->top - obj->base <= obj->statckSize)
    {
        *(obj->top) = x;
        obj->top++;
    }
    else
    {
        exit(1);
    }
}

void minStackPop(MinStack* obj) {
    if(obj->top != obj->base)
    {
        obj->top--;
    }
    else
    {
        exit(1);
    }
}

int minStackTop(MinStack* obj) {
    return *(obj->top);
}

int minStackGetMin(MinStack* obj) {
    int min;
    int *top = obj->top;
    int *base = obj->base;
    min = *top;
    while((top--) != base)
    {
        if(*top < min)
            min = *top;
    }
    return min;
}

void minStackFree(MinStack* obj) {
    free(obj->base);
    free(obj);
}

设计一个支持 push，pop，top 操作，并能在常数时间内检索到最小元素的栈。

• push(x) -- 将元素 x 推入栈中。
• pop() -- 删除栈顶的元素。
• top() -- 获取栈顶元素。
• getMin() -- 检索栈中的最小元素。

示例:

MinStack minStack = new MinStack();
minStack.push(-2);
minStack.push(0);
minStack.push(-3);
minStack.getMin();   --> 返回 -3.
minStack.pop();
minStack.top();      --> 返回 0.
minStack.getMin();   --> 返回 -2.