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railway.h
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40 lines (37 loc) · 897 Bytes
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/*
一个队列按1 ~ n的顺序入栈，给定另外一个顺序，问可不可能按此顺序出栈
*/
const int MAXN = 1000 + 10;
bool possible(int *target, int n) {
stack<int> s;
int A = 1, B = 1;
int ok = 1;
while (B <= n) {
if (A == target[B]) {
A++; B++;
} else if (!s.empty() && s.top() == target[B]) {
s.pop(); B++;
} else if (A <= n)
s.push(A++);
else {
ok = 0; break;
}
}
return ok;
}
void test() {
int n, target[MAXN];
while (cin >> n && n) {
memset(target, 0, sizeof(target));
cin >> target[1];
if (!target[1]) {
cout << endl;
break;
}
for (int i = 2; i <= n; i++) {
cin >> target[i];
}
bool f = possible(target, n);
cout << (f ? "Yes" : "No") << endl;
}
}