#include <bits/stdc++.h> using namespace std; const int INF = 1e9; int n,a[1000010],b[1000010]; char ans[1000010] = {}; using Interval = pair<int,int>; Interval dp[1000010][2]; void merge(Interval &t1,const Interval &t2,int offset){ t1 = Interval(min(t1.first,t2.first + offset),max(t1.second,t2.second + offset)); } signed main(){ scanf("%d",&n); for(int i = 0;i < 2 * n;i++) scanf("%d",&a[i]); for(int i = 0;i < 2 * n;i++) scanf("%d",&b[i]); for(int i = 0;i < 2 * n;i++) dp[i][0] = dp[i][1] = Interval(INF,-INF); dp[0][0] = Interval(1,1); dp[0][1] = Interval(0,0); for(int i = 0;i < 2 * n - 1;i++){ if(a[i] <= a[i + 1]) merge(dp[i + 1][0],dp[i][0],1); if(a[i] <= b[i + 1]) merge(dp[i + 1][1],dp[i][0],0); if(b[i] <= a[i + 1]) merge(dp[i + 1][0],dp[i][1],1); if(b[i] <= b[i + 1]) merge(dp[i + 1][1],dp[i][1],0); } int used = n,nxt = INF; for(int i = 2 * n - 1;i >= 0;i--){ if(dp[i][0].first <= used && used <= dp[i][0].second && a[i] <= nxt){ ans[i] = 'A'; used--; nxt = a[i]; }else if(dp[i][1].first <= used && used <= dp[i][1].second && b[i] <= nxt){ ans[i] = 'B'; nxt = b[i]; }else{ puts("-1"); return 0; } } printf("%s\n",ans); }

building4.cpp: In function 'int main()':
building4.cpp:16:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |         scanf("%d",&n);
      |         ~~~~~^~~~~~~~~
building4.cpp:17:43: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |         for(int i = 0;i < 2 * n;i++) scanf("%d",&a[i]);
      |                                      ~~~~~^~~~~~~~~~~~
building4.cpp:18:43: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |         for(int i = 0;i < 2 * n;i++) scanf("%d",&b[i]);
      |                                      ~~~~~^~~~~~~~~~~~