#include
#include
#include
int n; char str[10]; int top; int stack[10010]; int main(){ freopen("input.txt","r",stdin); while(scanf("%d",&n)!=EOF&&n){ top=-1; memset(stack,0,sizeof(stack)); for (int i = 0; i < n; ++i) { scanf("%s",str); if (str[0]=='A') { if (top>=0) printf("%d\n",stack[top]); else printf("E\n"); }else if(str[0]=='P'){ int tmp; scanf("%d",&tmp); stack[++top]=tmp; }else if (top>=0) top--; } printf("\n"); } return 0; }
九度OJ-1108-堆栈的使用
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