LRJ-Example-06-02-Uva514

 #define _CRT_SECURE_NO_WARNINGS

 #include<cstdio>
 #include<stack>
 using namespace std;
 const int MAXN =  + ;

 int n, target[MAXN];

 int main() {
     // scanf() returns the number of input items matched and assigned
     while (scanf("%d", &n) ==  && n != ) {
         while (true) {
             // the last line of the block contains just 0
             scanf("%d", &target[]);
             if (target[] == ) { printf("\n"); break; }

             for (int i = ; i <= n; i++)
                 scanf("%d", &target[i]);

             stack<int> s;
             // assume an input array input[] containing 1, 2, ..., n in sequence, input[i] == i
             // A is the index of input[], and B is the index of target[]
             int A = , B = ;
             bool ok = true;
             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 = false;
                     break;
                 }
             }

             printf("%s\n", ok ? "Yes" : "No");
         }
     }
     return ;
 }