Submission #224681

#	Time	Username	Problem	Language	Result	Execution time	Memory
224681		PeppaPig	Election Campaign (JOI15_election_campaign)	C++14	30 / 100	1095 ms	29480 KiB

election_campaign

#include <bits/stdc++.h>

#define long long long
#define iii tuple<int, int, int>
#define pii pair<int, int>
#define x first
#define y second

using namespace std;

const int N = 1e5+5;

struct SegmentTree {
    int t[N << 1];
    void update(int x, long k) {
        for(t[x += N] += k; x != 1; x >>= 1) 
            t[x >> 1] = t[x] + t[x ^ 1];
    }
    long query(int l, int r) {
        long ret = 0;
        for(l += N, r += N + 1; l < r; l >>= 1, r >>= 1) {
            if(l & 1) ret += t[l++];
            if(r & 1) ret += t[--r];
        }
        return ret;
    }
} T;

int n, q;
vector<int> g[N];
vector<iii> Q[N];

int dep[N], par[N], rot[N], spi[N], pos[N], anc[N][18];

int dfs(int u, int p) {
    dep[u] = dep[p] + 1, par[u] = anc[u][0] = p;
    for(int i = 1; i <= 17; i++) anc[u][i] = anc[anc[u][i-1]][i-1];
    int sz = 0; pii ret(0, -1);
    for(int &v : g[u]) if(v != p) {
        int z = dfs(v, u);
        sz += z, ret = max(ret, pii(z, v));
    }
    spi[u] = ret.y;
    return sz;
}

void init_hld() {
    dfs(1, 0);
    for(int i = 1, idx = 0; i <= n; i++) if(spi[par[i]] != i) 
        for(int j = i; j != -1; j = spi[j])
            pos[j] = ++idx, rot[j] = i;
}

int lca(int a, int b) {
    if(dep[a] < dep[b]) swap(a, b);
    for(int i = 17; ~i; i--) if(dep[anc[a][i]] >= dep[b]) a = anc[a][i];
    if(a == b) return a;
    for(int i = 17; ~i; i--) if(anc[a][i] != anc[b][i]) a = anc[a][i], b = anc[b][i];
    return anc[a][0];
}

int pre(int a, int b) {
    for(int i = 17; ~i; i--) if(dep[anc[a][i]] > dep[b])
        a = anc[a][i];
    return a;
}

long dp[N], ans;

long query_path(int a, int b) {
    long ret = spi[a] != -1 ? dp[spi[a]] : 0;
    while(rot[a] != rot[b]) {
        ret += T.query(pos[rot[a]], pos[a]) - dp[rot[a]];
        if(spi[par[rot[a]]] != -1) ret += dp[spi[par[rot[a]]]];
        a = par[rot[a]];
    }
    ret += T.query(pos[b], pos[a]);
    return ret;
}

void solve(int u, int p) {
    long sum = 0;
    for(int &v : g[u]) if(v != p) {
        solve(v, u);
        sum += dp[v];
    }
    dp[u] = sum;
    for(iii &t : Q[u]) {
        int a, b, c; tie(a, b, c) = t;
        long now = sum;
        if(a != u) {
            int pa = pre(a, u);
            now += query_path(a, pa) - dp[pa];
        }
        if(b != u) {
            int pb = pre(b, u);
            now += query_path(b, pb) - dp[pb];
        }
        dp[u] = max(dp[u], now + c);
    }
    ans = max(ans, dp[u]);
    if(rot[u] == u) T.update(pos[par[u]], dp[u]);
}

int main() {
    scanf("%d", &n);
    for(int i = 1, a, b; i < n; i++) {
        scanf("%d %d", &a, &b);
        g[a].emplace_back(b);
        g[b].emplace_back(a);
    }
    init_hld();

    scanf("%d", &q);
    for(int i = 1, a, b, c; i <= q; i++) {
        scanf("%d %d %d", &a, &b, &c);
        Q[lca(a, b)].emplace_back(a, b, c);
    }
    solve(1, 0);
    printf("%lld\n", ans);

    return 0;
}

Compilation message (stderr)

election_campaign.cpp: In function 'int main()':
election_campaign.cpp:106:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
election_campaign.cpp:108:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &a, &b);
         ~~~~~^~~~~~~~~~~~~~~~~
election_campaign.cpp:114:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &q);
     ~~~~~^~~~~~~~~~
election_campaign.cpp:116:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d %d", &a, &b, &c);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 0 / 30
• Subtask 5: 10 / 10
• Subtask 6: 0 / 40