SOJ 1021 Couples

The main topic: N (1≤n≤100000) couples form a ring, numbered 1 to 2n. Adjacent couples can be removed from the ring, if you can delete all couples, then output yes, otherwise output No. There are multiple sets of test styles, and when n equals 0 o'clock, the input ends.

Problem-solving ideas: Reverse thinking, in the process of generating loops, instead of deleting the couple after generating the ring.

Data structure used: stack.

The code is as follows:

#include <iostream>#include<stack>#include<map>using namespacestd;intMain () {intn, nn;  while(Cin >> N, n! =0) {Stack<int>St; Map<int,int>m; //read into the couple's        intW, H;  for(inti =0; I < n; i++) {cin>> W >>h; M[W]=h; M[H]=W; } NN= n *2;  for(inti =1; I <= nn; i++) {//couple number starting from 1 to n*2            if(!st.empty () && st.top () = =M[i])            {St.pop (); } Else{St.push (i); }        }        if(St.empty ()) {cout<<"Yes"<<Endl; } Else{cout<<"No"<<Endl; }    }    return 0;}

SOJ 1021 Couples