#include <stack>
#include <iostream>

using namespace std;

int main(void) {
	int arr[1010], n, i, flag;
	stack<int> a;
	stack<int> b;

	while (cin >> n) {
		if (!n)		break;
		while (cin >> arr[0]) {
		if (!arr[0]) {
			cout << endl;
			break;
		} 
		for (i = 1; i < n; i++)
			cin >> arr[i];
		for (i = n; i > 0; i--)
			a.push(i);
		flag = 1;
		i = 0;
		while (i < n) {
			if (b.empty()) {
				if (a.top() == arr[i]) {
					i++;
					a.pop();
				} else {
					b.push(a.top());
					a.pop();
				}
			} else {
				if (b.top() == arr[i]) {
					i++;
					b.pop();
				} else {
					if (a.empty()) {
						flag = 0;
						break;
					} else {
						b.push(a.top());
						a.pop();
					}
				}
			}
		}
		if (flag)
			cout << "Yes" << endl;
		else
			cout << "No" << endl;
		}
	}
	return 0;
}

• 你晕啊，这样的错都犯 (0) ecbtnrt 2008-05-29 21:18:39