ui自学网站/高端营销型网站建设

思路比较简单。就是当要pop的时候，如果s2为空，才把s1的转过来。总之就是区分一下此时s2为空和非空的情况。 http://ac.jobdu.com/problem.php?pid=1512

#include <cstring>
#include <cstdio>
#include <stack>
using namespace std;class Queue {
public:void push(int val) {s1.push(val);}int pop() {if (s2.empty()){while(!s1.empty()){int tmp = s1.top();s1.pop();s2.push(tmp);}}if (!s2.empty()) {      int tmp = s2.top();s2.pop();return tmp;}else {return -1;}}
private:stack<int> s1, s2;
};int main() {Queue Q;int n; scanf("%d", &n);char flag[20]; int val;for (int i=0; i<n; ++i) {scanf("%s", flag);if (strcmp("PUSH", flag) == 0) {scanf("%d", &val);Q.push(val);} else if (strcmp("POP", flag) == 0) {printf("%d\n", Q.pop());}}return 0;
}