Submission #240012

#	Time	Username	Problem	Language	Result	Execution time	Memory
240012		karma	Dynamic Diameter (CEOI19_diameter)	C++14	100 / 100	4552 ms	155396 KiB

diameter

#include <bits/stdc++.h>
#define pb          emplace_back
#define ll          long long
#define fi          first
#define se          second
#define mp          make_pair
//#define int         int64_t

using namespace std;

const int N = (int)1e5 + 2;
const ll inf = 1ll << 60;
typedef pair<int, int> pii;

int lg[N];
struct TTree { /// get max value in range, add x in a range
    vector<pair<ll, int>> st;
    vector<ll> lz;
    vector<pii> range;
    int n, h; ll val;
    pair<ll, int> top;
    void init(int _n) {
        n = _n; h = sizeof(int) * 8 - __builtin_clz(n);
        st.resize(2 * n + 2, mp(0, 0));
        lz.resize(2 * n + 2, 0);
        for(int i = n - 1; i >= 0; --i) st[i + n].se = i;
    }
    void apply(int x, ll val) {
        st[x].fi += val;
        if(x < n) lz[x] += val;
    }
    inline pair<ll, int> Max(const pair<ll, int>& x, const pair<ll, int>& y) {
        if(x.fi < y.fi) return y;
        return x;
    }
    void build(int x) {
        while(x > 1) {
            x >>= 1;
            st[x] = Max(st[x << 1], st[x << 1 | 1]);
            st[x].fi += lz[x];
        }
    }
    void push(int x) {
        for(int i, s = h; s > 0; --s) {
            i = x >> s;
            if(lz[i] != 0) {
                apply(x << 1, lz[i]);
                apply(x << 1 | 1, lz[i]);
                lz[i] = 0;
            }
        }
    }
    void upd(int l, int r, ll val) {
        l += n, r += (n + 1);
        int l0 = l, r0 = r;
        for(; l < r; l >>= 1, r >>= 1) {
            if(l & 1) apply(l ++, val);
            if(r & 1) apply(-- r, val);
        }
        build(l0); build(r0 - 1);
    }
    ll diameter() {
        top = st[1]; val = st[1].fi;
        upd(range[top.se].fi, range[top.se].se, -top.fi);
        val += max(st[1].fi, 0ll);
        upd(range[top.se].fi, range[top.se].se, top.fi);
        return val;
    }
};
vector<TTree> it;

struct TEdge {
    int u, v; ll w;
    vector<int> it;
    vector<pii> range;
} e[N];
vector<pii> adj[N];
ll W, dis[N];
int n, q, Time, head[N], in[N], out[N], sz[N], big[N];
bool del[N];

int find(int u) {
    function<void(int, int)> dfs = [&](int u, int p) {
        sz[u] = 1, big[u] = 0;
        for(auto v: adj[u]) {
            if(v.fi == p || del[v.fi]) continue;
            dfs(v.fi, u);
            sz[u] += sz[v.fi];
            if(sz[v.fi] > sz[big[u]]) big[u] = v.fi;
        }
    };
    dfs(u, -1);
    int cen = u;
    while(sz[big[cen]] * 2 >= sz[u] && big[cen]) cen = big[cen];
    return cen;
}

multiset<ll, greater<ll>> ans;
void centroid(int u) {
    int root = find(u);
    it.push_back({});
    function<void(int, int)> dfs = [&](int u, int p) {
        in[u] = ++Time;
        if(p == root) head[u] = u;
        else if(p != -1) head[u] = head[p];
        for(auto v: adj[u]) {
            if(del[v.fi] || v.fi == p) continue;
            dis[v.fi] = dis[u] + e[v.se].w;
            it.back().range.pb(v.se, v.fi);
            dfs(v.fi, u);
        }
        out[u] = Time;
    };
    Time = -2, dis[root] = 0;
    dfs(root, -1); del[root] = 1;
    if((int)it.back().range.size()) {
        it.back().init((int)it.back().range.size());
        for(auto& p: it.back().range) {
            e[p.fi].it.pb((int)it.size() - 1);
            e[p.fi].range.pb(in[p.se], out[p.se]);
            it.back().upd(in[p.se], in[p.se], dis[p.se]);
            p.fi = in[head[p.se]], p.se = out[head[p.se]];
        }
        ans.insert(it.back().diameter());
    }
    for(auto v: adj[root]) {
        if(del[v.fi]) continue;
        centroid(v.fi);
    }
}

///40071305542068

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    #define Task        "test"
    if(fopen(Task".inp", "r")) {
        freopen(Task".inp", "r", stdin);
        freopen(Task".out", "w", stdout);
    }
    cin >> n >> q >> W;
    for(int i = 1; i <= n; ++i) lg[i] = log2(i) + 1;
    for(int i = 0; i < n - 1; ++i) {
        cin >> e[i].u >> e[i].v >> e[i].w;
        adj[e[i].u].pb(e[i].v, i);
        adj[e[i].v].pb(e[i].u, i);
    }
    centroid(1); ll w, lst = 0;
    for(int id, tree; q > 0; --q) {
        cin >> id >> w;
        id = ((ll)id + lst) % (n - 1);
        w = (w + lst) % W;
        for(int i = 0; i < e[id].it.size(); ++i) {
            tree = e[id].it[i];
            ans.erase(ans.find(it[tree].diameter()));
            it[tree].upd((int)e[id].range[i].fi, (int)e[id].range[i].se, w - e[id].w);
            ans.insert(it[tree].diameter());
        }
        e[id].w = w;
        cout << (lst = *ans.begin()) << '\n';
    }
}

Compilation message (stderr)

diameter.cpp: In function 'int32_t main()':
diameter.cpp:154:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i = 0; i < e[id].it.size(); ++i) {
                        ~~^~~~~~~~~~~~~~~~~
diameter.cpp:139:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
         freopen(Task".inp", "r", stdin);
         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
diameter.cpp:140:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
         freopen(Task".out", "w", stdout);
         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
diameter.cpp: In function 'void centroid(int)':
diameter.cpp:104:29: warning: array subscript is below array bounds [-Warray-bounds]
         if(p == root) head[u] = u;
                       ~~~~~~^

• Subtask 1: 11 / 11
• Subtask 2: 13 / 13
• Subtask 3: 7 / 7
• Subtask 4: 18 / 18
• Subtask 5: 24 / 24
• Subtask 6: 27 / 27