#include "gift.h" #include <bits/stdc++.h> const int N = 5e5+10; int sweep[N], mx[N]; int construct(int n, int r, std::vector<int> a, std::vector<int> b, std::vector<int> x) { using namespace std; string s = ""; for(int i = 0; i < r; ++i){ if(x[i] == 1) sweep[a[i]]++, sweep[b[i]]--; } char c[] = {'R', 'B'}; int cur = 0; for(int i = 0; i < n; ++i){ sweep[i+1] += sweep[i]; mx[i] = -1; s += c[cur]; if(sweep[i] == 0)cur ^= 1; } for(int i = 0; i < r; ++i){ if(x[i] == 2) mx[b[i]] = max(mx[b[i]], a[i]); } int last_change = -1; for(int i = 0; i < n; ++i){ if(i > 0 && s[i] != s[i-1]) last_change = i-1; if(last_change < mx[i]) return 0; } craft(s); return 1; }