#include <bits/stdc++.h> #define pii pair<int, int> #define x first #define y second using namespace std; const int N = 2e5+5; int n, m; int x[N], y[N]; int s[N], t[N]; int za[N], zb[N]; bool state[N][4]; int idx; map<pii, int> Mp; int par[N<<1]; int find(int u) { return par[u] = par[u] == u ? u : find(par[u]); } void merge(int a, int b, int c, int d) { int u = Mp[pii(a, b)], v = Mp[pii(c, d)]; par[find(u)] = find(v); } int main() { iota(par, par+(N<<1), 0); scanf("%d", &n); int mnx = 1e9, st; for(int i = 0; i < n; ++i) { scanf("%d %d", x+i, y+i); Mp[pii(x[i], y[i])] = ++idx; Mp[pii(x[i]+1, y[i])] = ++idx; Mp[pii(x[i], y[i]+1)] = ++idx; Mp[pii(x[i]+1, y[i]+1)] = ++idx; if(x[i] < mnx) mnx = x[i], st = i; } scanf("%d", &m); for(int i = 0; i < m; ++i) { scanf("%d %d", s+i, t+i), s[i]--, t[i]--; if(x[s[i]] > x[t[i]]) swap(s[i], t[i]); if(y[s[i]] > y[t[i]]) swap(s[i], t[i]); if(x[s[i]] != x[t[i]]) { state[s[i]][1] = state[t[i]][3] = true; merge(x[s[i]]+1, y[s[i]], x[t[i]], y[t[i]]); merge(x[s[i]]+1, y[s[i]]+1, x[t[i]], y[t[i]]+1); } else { state[s[i]][0] = state[t[i]][2] = true; merge(x[s[i]], y[s[i]]+1, x[t[i]], y[t[i]]); merge(x[s[i]]+1, y[s[i]]+1, x[t[i]]+1, y[t[i]]); } } for(int i = 0; i < n; ++i) { if(!state[i][0]) merge(x[i], y[i]+1, x[i]+1, y[i]+1); if(!state[i][1]) merge(x[i]+1, y[i], x[i]+1, y[i]+1); if(!state[i][2]) merge(x[i], y[i], x[i]+1, y[i]); if(!state[i][3]) merge(x[i], y[i], x[i], y[i]+1); } for(int i = 0; i < m; ++i) { int a, b; if(x[s[i]] != x[t[i]]) a = find(Mp[pii(x[s[i]]+1, y[s[i]])]), b = find(Mp[pii(x[s[i]]+1, y[s[i]]+1)]); else a = find(Mp[pii(x[s[i]], y[s[i]]+1)]), b = find(Mp[pii(x[s[i]]+1, y[s[i]]+1)]); za[i] = a, zb[i] = b; g[a].emplace_back(i), g[b].emplace_back(i); } int start = find(Mp[pii(x[st], y[st])]); Mp.clear(); }

flood.cpp: In function 'int main()':
flood.cpp:66:9: error: 'g' was not declared in this scope
         g[a].emplace_back(i), g[b].emplace_back(i);
         ^
flood.cpp:68:9: warning: unused variable 'start' [-Wunused-variable]
     int start = find(Mp[pii(x[st], y[st])]);
         ^~~~~
flood.cpp:28:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
flood.cpp:31:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", x+i, y+i);
         ~~~~~^~~~~~~~~~~~~~~~~~~
flood.cpp:38:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &m);
     ~~~~~^~~~~~~~~~
flood.cpp:40:41: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", s+i, t+i), s[i]--, t[i]--;
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~