Stack Summary

Leetcode Stack practice summary

1

1.1 Min Stack

#define STACK_INIT_SIZE 1000 //Stack初始大小
#define STACKINCREMENT 100 //空间耗尽时，的增量。
#define SElemType int //指定元素类型

typedef struct {
    SElemType* base;
    SElemType* top;
    int stacksize;    
} MinStack;

/** initialize your data structure here-> */

MinStack* minStackCreate() {
    MinStack* S = (MinStack*)malloc(sizeof(MinStack));
    if (!S)
        return NULL;
    S->base = (SElemType*)malloc(STACK_INIT_SIZE * sizeof(SElemType));
    if(!S->base)
        return NULL;
    S->top = S->base;
    S->stacksize = STACK_INIT_SIZE;
    return S;
}

void minStackPush(MinStack* obj, int x) {
    ///////////如果存储空间耗尽///////////////
    if((obj->top - obj->base) >= obj->stacksize){
    obj->base = (SElemType*)realloc(obj->base,(obj->stacksize + STACKINCREMENT)*sizeof(SElemType));
    if(!obj->base)
        return;
    obj->top = obj->base + obj->stacksize;
    obj->stacksize = obj->stacksize + STACKINCREMENT;
    }
    //////////END////////////////////////////

    *(obj->top++) = x;  //入栈
}

void minStackPop(MinStack* obj) {
    ////////////如果栈空///////
    if(obj->top == obj->base)
        return;
    /////////////END/////////////
    obj->top--;  //出栈
}

int minStackTop(MinStack* obj) {
    if(obj->top == obj->base)
        return NULL;
    return *(obj->top-1);

}

int minStackGetMin(MinStack* obj) {
    SElemType* min;

    min = obj->base;

    for(SElemType* curr=obj->top; curr != obj->base; curr--){
        if(*(curr-1) < *min)
           min = curr-1;
    }
    return *min;  
}

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

    free(obj);
    }
}

Stack的基本操作。