Ultraviolet (use of stack) 514 rails

Exercise the usage of the stack and pay attention to the input format. I have not understood it for a long time.

 

 1 //#define LOCAL 2 #include <iostream> 3 #include <cstdio> 4 #include <cstring> 5 #include <stack> 6 using namespace std; 7  8 const int maxn = 1000 + 10; 9 int n, target[maxn];10 11 int main(void)12 {13     #ifdef LOCAL14         freopen("514in.txt", "r", stdin);15     #endif16 17     while(scanf("%d", &n) == 1 && n)18     {19         while(scanf("%d", &target[1]) == 1 && target[1])20         {21             for(int i = 2; i <= n; ++i)    scanf("%d", &target[i]);22             stack<int> s;23             int A = 1, B = 1;24             int ok = 1;25             while(B <= n)26             {27                 if(A == target[B])    { A++; B++; }28                 else if(!s.empty() && s.top() == target[B])    { s.pop(); B++; }29                 else if(A <= n) s.push(A++);30                 else    { ok = 0; break; }31             }32             printf("%s\n", ok ? "Yes" : "No");33         }34         printf("\n");35     }36 37     return 0;38 }

Code Jun

 

Ultraviolet (use of stack) 514 rails