Submission #22667026

---

Source Code Expand

#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()
//#pragma GCC optimize ("-O3")
using namespace std;
void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); }
typedef long long ll; const int inf = INT_MAX / 2; const ll infl = 1LL << 60;
template<class T>bool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; }
//---------------------------------------------------------------------------------------------------
struct HLDecomposition {
    vector<set<int>> g; vector<int> vid, head, heavy, parent, depth, inv, in, out;
    HLDecomposition() {} HLDecomposition(int n) { init(n); }
    void init(int n) {
        g.resize(n); vid.resize(n, -1); head.resize(n); heavy.resize(n, -1);
        parent.resize(n); depth.resize(n); inv.resize(n); in.resize(n); out.resize(n);
    }
    void add(int u, int v) { g[u].insert(v); g[v].insert(u); }
	void build(int root) { dfs(root, -1); t = 0; dfs_hld(root); }

    int dfs(int curr, int prev) {
        parent[curr] = prev; int sub = 1, max_sub = 0;
        heavy[curr] = -1;
        for (int next : g[curr]) if (next != prev) {
            depth[next] = depth[curr] + 1;
            int sub_next = dfs(next, curr); sub += sub_next;
            if (max_sub < sub_next) max_sub = sub_next, heavy[curr] = next;
        }return sub;
    }

    int t = 0;
    void dfs_hld(int v = 0)
    {
        vid[v] = in[v] = t;
        t++;
        inv[in[v]] = v;
        if (0 <= heavy[v]) {
            head[heavy[v]] = head[v];
            dfs_hld(heavy[v]);
        }
        for (auto u : g[v]) if(depth[v] < depth[u])  if (u != heavy[v]) {
            head[u] = u;
            dfs_hld(u);
        }
        out[v] = t;
    }


    void foreach(int u, int v, function<void(int, int)> f) { // [x,y]
        if (vid[u] > vid[v]) swap(u, v); f(max(vid[head[v]], vid[u]), vid[v]);
        if (head[u] != head[v]) foreach(u, parent[head[v]], f);
    }
    int ancestor(int from, int times) {
        while (true) {
            if (depth[head[from]] > depth[from] - times) {
                times -= depth[from] - depth[head[from]] + 1; if (head[from] == 0)return -1; from = parent[head[from]];
            }
            else return inv[vid[from] - times];
        }
    }
    int lca(int u, int v) {
        if (vid[u] > vid[v]) swap(u, v); if (head[u] == head[v]) return u;
        return lca(u, parent[head[v]]);
    }
    int distance(int u, int v) { return depth[u] + depth[v] - 2 * depth[lca(u, v)]; }
    int child(int parent, int child, int times) {
        assert(depth[parent]<depth[child]);
        int d = distance(parent, child); assert(times - 1 <= d); return ancestor(child, d - times);
    }
    int go(int from, int to, int times) {
        int d = distance(from, to); assert(0 <= times and times <= d);
        int lc = lca(from, to); if (lc == to)return ancestor(from, times); if (lc == from)return child(from, to, times);
        int dd = distance(from, lc); if (dd <= times)return go(lc, to, times - dd); return ancestor(from, times);
    }
};
/*---------------------------------------------------------------------------------------------------
　　　　　　　　　　　 ∧＿∧
　　　　　 ∧＿∧ 　（´<_｀ ）　 Welcome to My Coding Space!
　　　　 （ ´_ゝ`）　/　 ⌒i     @hamayanhamayan0
　　　　／　　　＼　 　  |　|
　　　 /　　 /￣￣￣￣/　　|
　 ＿_(__ﾆつ/　    ＿/ .| .|＿＿＿＿
　 　　　＼/＿＿＿＿/　（u　⊃
---------------------------------------------------------------------------------------------------*/










/*


int d[V][V];
REP(i, V) REP(j, V)
{
    if (i == j)
        d[i][j] = 0;
    else
        d[i][j] = INF;
}
// ここで辺のコストを指定
rep(k, 0, N) rep(i, 0, N) rep(j, 0, N) chmin(D[i][j], D[i][k] + D[k][j]);



*/



int N, M;
vector<int> E[101010];
int Q;
HLDecomposition hld;
map<int, map<int, int>> D;
//---------------------------------------------------------------------------------------------------
vector<pair<int, int>> unused;
bool vis[101010];
void dfs(int cu, int pa = -1) {
    vis[cu] = true;
    fore(to, E[cu]) if (to != pa) {
        if (vis[to]) {
            unused.push_back({ cu, to });
            continue;
        }

        hld.add(cu, to);
        dfs(to, cu);
    }
}
//---------------------------------------------------------------------------------------------------
void _main() {
    cin >> N >> M;
    rep(i, 0, M) {
        int a, b; cin >> a >> b;
        a--; b--;
        E[a].push_back(b);
        E[b].push_back(a);
    }

    hld.init(N);
    dfs(0);
    hld.build(0);

    vector<int> targets;
    fore(p, unused) {
        targets.push_back(p.first);
        targets.push_back(p.second);
    }
    sort(all(targets));
    targets.erase(unique(all(targets)), targets.end());

    fore(x, targets) fore(y, targets) D[x][y] = hld.distance(x, y);
    fore(p, unused) D[p.first][p.second] = D[p.second][p.first] = 1;
    fore(k, targets) fore(i, targets) fore(j, targets) chmin(D[i][j], D[i][k] + D[k][j]);

    cin >> Q;
    rep(i, 0, Q) {
        int u, v; cin >> u >> v;
        u--; v--;

        int ans = hld.distance(u, v);
        fore(x, targets) fore(y, targets) chmin(ans, hld.distance(u, x) + D[x][y] + hld.distance(y, v));
        printf("%d\n", ans);
    }
}

Submission Info

Compile Error

./Main.cpp: In member function ‘void HLDecomposition::foreach(int, int, std::function<void(int, int)>)’:
./Main.cpp:52:9: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
   52 |         if (vid[u] > vid[v]) swap(u, v); f(max(vid[head[v]], vid[u]), vid[v]);
      |         ^~
./Main.cpp:52:42: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’
   52 |         if (vid[u] > vid[v]) swap(u, v); f(max(vid[head[v]], vid[u]), vid[v]);
      |                                          ^
./Main.cpp: In member function ‘int HLDecomposition::lca(int, int)’:
./Main.cpp:64:9: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
   64 |         if (vid[u] > vid[v]) swap(u, v); if (head[u] == head[v]) return u;
      |         ^~
./Main.cpp:64:42: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’
   64 |         if (vid[u] > vid[v]) swap(u, v); if (head[u] == head[v]) return u;
      |                                          ^~

Judge Result