HDU - 5385 The path
先把1加入点集进行扩展, 然后两头分别从2和n开始往里加元素, 使得随着时间dis[ i ] 递增即可。
#include<bits/stdc++.h> #define LL long long #define LD long double #define ull unsigned long long #define fi first #define se second #define mk make_pair #define PLL pair<LL, LL> #define PLI pair<LL, int> #define PII pair<int, int> #define SZ(x) ((int)x.size()) #define ALL(x) (x).begin(), (x).end() #define fio ios::sync_with_stdio(false); cin.tie(0); using namespace std; const int N = 1e5 + 7; const int inf = 0x3f3f3f3f; const LL INF = 0x3f3f3f3f3f3f3f3f; const int mod = 1e9 + 7; const double eps = 1e-8; const double PI = acos(-1); template<class T, class S> inline void add(T &a, S b) {a += b; if(a >= mod) a -= mod;} template<class T, class S> inline void sub(T &a, S b) {a -= b; if(a < 0) a += mod;} template<class T, class S> inline bool chkmax(T &a, S b) {return a < b ? a = b, true : false;} template<class T, class S> inline bool chkmin(T &a, S b) {return a > b ? a = b, true : false;} mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); int n, m, d[N], U[N], V[N], ans[N]; bool vis[N]; vector<PII> G[N]; set<PII> Set; void init() { Set.clear(); for(int i = 1; i <= n; i++) { G[i].clear(); vis[i] = false; } } int main() { int T; scanf("%d", &T); while(T--) { scanf("%d%d", &n, &m); init(); for(int i = 1; i <= m; i++) { int u, v; scanf("%d%d", &u, &v); U[i] = u; V[i] = v; G[u].push_back(mk(i, v)); ans[i] = n; } d[1] = 0; vis[1] = true; for(auto &e : G[1]) { if(vis[e.se]) continue; vis[e.se] = true; Set.insert(mk(e.se, e.fi)); } int tim = 1, big = n, sml = 2; while(SZ(Set)) { if(Set.begin()->fi == sml) { int eid = Set.begin()->se; Set.erase(*Set.begin()); d[sml] = tim; ans[eid] = d[sml] - d[U[eid]]; for(auto &e : G[sml]) { if(vis[e.se]) continue; vis[e.se] = true; Set.insert(mk(e.se, e.fi)); } sml++; } else if(Set.rbegin()->fi == big) { int eid = Set.rbegin()->se; Set.erase(*Set.rbegin()); d[big] = tim; ans[eid] = d[big] - d[U[eid]]; for(auto &e : G[big]) { if(vis[e.se]) continue; vis[e.se] = true; Set.insert(mk(e.se, e.fi)); } big--; } else { assert(0); } tim++; } for(int i = 1; i <= m; i++) { printf("%d\n", ans[i]); } } return 0; } /* */