#include "bits/stdc++.h" using namespace std; #define double long double const int MAXN = 9500000; const int MOD = 1e9 + 7; mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count()); int rnd(int x, int y) { int u = uniform_int_distribution<int>(x, y)(rng); return u; } int bm(int b, int p) { if(p==0) return 1 % MOD; int r = bm(b, p >> 1); if(p&1) return (((r*r) % MOD) * b) % MOD; return (r*r) % MOD; } int inv(int b) { return bm(b, MOD-2); } int fastlog(int x) { return (x == 0 ? -1 : 64 - __builtin_clzll(x) - 1); } void printcase(int i) { cout << "Case #" << i << ": "; } vector<int>adj[MAXN]; int n, m, s, nxt; void construct(int b, int p) { for(int j=b%p; j<n; j+=p) { if(j+p < n) adj[nxt + j/p].push_back((nxt + j/p + 1) * 2 + 1); if(j-p >= 0) adj[nxt + j/p].push_back((nxt + j/p - 1) * 2 + 1); adj[nxt + j/p].push_back(j * 2 + 0); } adj[b].push_back((nxt + b/p) * 2 + 0); for(int j=b%p; j<n; j+=p) { nxt++; } } void solve(int tc) { cin >> n >> m; s = sqrt(n); nxt = n; int st, en; int bruh[s+1][s]; for(int i=1; i<=s; i++) { for(int j=0; j<i; j++) { bruh[i][j] = -1; } } for(int i=0; i<m; i++) { int b, p; cin >> b >> p; if(i == 0) st = b; if(i == 1) en = b; if(p <= s && bruh[p][b%p] == -1) { bruh[p][b%p] = nxt; construct(b, p); } else if(p > s) { construct(b, p); } else { adj[b].push_back((bruh[p][b%p] + b/p) * 2 + 0); } } int k = nxt; int dist[k]; bool vis[k]; for(int i=0; i<k; i++) dist[i] = 1e9, vis[i] = 0; dist[st] = 0; deque<int> dq; dq.push_back(st); while(dq.size()) { int f = dq.front(); dq.pop_front(); if(!vis[f]) { vis[f] = 1; for(int x: adj[f]) { if(!vis[x / 2] && dist[x / 2] > dist[f] + (x % 2)) { dist[x / 2] = dist[f] + (x % 2); if(x % 2 == 0) dq.push_front(x / 2); else dq.push_back(x / 2); } } } } cout<<(dist[en]==1e9?-1:dist[en])<<"\n"; } int32_t main() { ios::sync_with_stdio(0); cin.tie(0); int t = 1; //cin >> t; for(int i=1; i<=t; i++) solve(i); } // 勿忘初衷

skyscraper.cpp: In function 'void solve(int)':
skyscraper.cpp:84:17: warning: 'en' may be used uninitialized in this function [-Wmaybe-uninitialized]
   84 |   cout<<(dist[en]==1e9?-1:dist[en])<<"\n";
      |          ~~~~~~~^