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MinStack.cpp
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MinStack.cpp
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#include<stdio.h>
#include<stdlib.h>
#define MAXSIZE 1000
int g_index=0;
int g_totalLen=0;
int g_minIndex=-1;
int g_minValue=INT_MAX;
MinStack *g_stack=NULL;
typedef struct {
int val;
} MinStack;
void minStackCreate(MinStack *stack, int maxSize) {
if(maxSize<1){
return;
}
stack=(MinStack *)malloc(maxSize*sizeof(MinStack));
if(stack==NULL){
exit(EXIT_FAILURE);
}
g_index=0;
g_totalLen=maxSize;
}
void minStackPush(MinStack *stack, int element) {
if(stack==NULL){//创建一个栈
minStackCreate(stack,MAXSIZE);
}
if(element<g_minValue){//更新最小值的位置
g_minIndex=g_index;
g_minValue=element;
}
if(g_index<g_totalLen){
stack[g_index].val=element;
g_index++;
}
else{//开辟一个2* maxSize的栈
MinStack *newstack=NULL;
int len=g_totalLen;
minStackCreate(newstack, g_totalLen*2);
//将stack中的元素拷贝到newStack
int i=0;
for(;i<len;i++){
newstack[i]=stack[i];
}
stack=newstack;
stack[len].val=element;
g_index=len+1;
}
}
void minStackPop(MinStack *stack) {
if(stack==NULL||g_index<=0){
return;
}
else{
g_index--;
//如果将最小值弹出去了,则重新找到最小值的位置
if(g_minIndex==g_index){
g_minValue=INT_MAX;
for(int i=0;i<g_index;i++){
if(stack[i].val<g_minValue){
g_minValue=stack[i].val;
g_minIndex=i;
}
}
}
}
}
int minStackTop(MinStack *stack) {
if(stack==NULL||g_index<=0){
return -1;
}
else{
return stack[g_index-1].val;
}
}
int minStackGetMin(MinStack *stack) {
if(stack==NULL||g_index<=0){//栈中是没有元素的
return 0;
}
return g_minValue;
}
void minStackDestroy(MinStack *stack) {
if(stack==NULL){
return;
}
free(stack);
stack==NULL;
}
int main(void){
MinStack *stack=NULL;
minStackPush(stack,-3);
int res=minStackGetMin(stack);
printf(" %d",res);
}