Submission #90995

#	Time	Username	Problem	Language	Result	Execution time	Memory
90995		blast	Evacuation plan (IZhO18_plan)	C++14	0 / 100	304 ms	18600 KiB

plan

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair < int, int > pii;
typedef pair < long long, long long > pll;

const int N = 1e5 + 7, inf = 1e9 + 7;
const ll INF = 1e18 + 7;

const int X[] = {1, -1, 0, 0};
const int Y[] = {0, 0, 1, -1};

int n, m, d[N], k, s, t, dist[N], p[N];
bool us[N];
int u[N], v[N], tin[N], tout[N], timer, up[N][27], w[N][27];
int dep[N];

vector < pii > g[N];
vector < pair < int, pii > > g1;
vector < pii > g2[N];

int get(int v) {
    if (v == p[v])
        return v;
    return p[v] = get(p[v]);
}

bool unite(int v, int u) {
    v = get(v), u = get(u);
    if (v != u) {
        p[v] = u;
        return 1;
    }
    return 0;
}

bool upper(int a, int b) {
    return tin[a] <= tin[b] && tout[a] >= tout[b];
}

void dfs(int v, int p = 0) {
    us[v] = 1;
    tin[v] = ++timer;
    up[v][0] = p;
    w[v][0] = min(d[v], d[p]);
    dep[v] = dep[p] + 1;
    for (int i = 1; i <= 20; i++) {
        up[v][i] = up[up[v][i - 1]][i - 1];
        w[v][i] = min(w[up[v][i - 1]][i - 1], w[v][i - 1]);
    }
    for (int i = 0; i < g2[v].size(); i++) {
        pii to = g2[v][i];
        if (to.first == p) {
            continue;
        }
        if (!us[to.first]) {
            dfs(to.first, v);
        }
    }
    tout[v] = ++timer;
}

int lca(int a, int b) {
    if (upper(a, b)) {
    	return a;	
    }
	if (upper(b, a)) {
		return b;
	}
	for (int i = 20; i >= 0; i--) {
		if (!upper(up[a][i], b)) {
			a = up[a][i]	;
		}
	}
	return up[a][0];	
}
                    	
int ans(int a, int b) {
    if (a == b) {
    	return inf;
    }                         
    int cur = w[a][0];
   	for (int i = 20; i >= 0; i--) {
        if (dep[up[a][i]] >= dep[b]) {
            cur = min(cur, w[a][i]);
            a = up[a][i];           
        }
    }
    return cur;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        d[i] = inf;
    }
    for (int i = 1, x; i <= m; i++) {
        cin >> u[i] >> v[i] >> x;
        g[u[i]].push_back(make_pair(v[i], x));
        g[v[i]].push_back(make_pair(u[i], x));
    }
    set < pair <int, int> > st;
    cin >> k;
    for (int i = 1, x; i <= k; i++) {
        cin >> x;
        d[x] = 0;
        st.insert(make_pair(0, x));
    }
    while(!st.empty()) {
        int x = st.begin() -> second;
        st.erase(st.begin());
        for (int i = 0; i < g[x].size(); ++i) {
            int to = g[x][i].first, len = g[x][i].second;
            if (d[x] + len < d[to]) {
                st.erase(make_pair(d[to], to));
                d[to] = d[x] + len;
                st.insert(make_pair(d[to], to));
            }
        }
    }
    for (int i = 1; i <= m; i++) {
        g1.push_back(make_pair(min(d[u[i]], d[v[i]]), make_pair(u[i], v[i])));
    }
    for (int i = 1; i <= n; ++i) {
        p[i] = i;
    }
    sort(g1.begin(), g1.end());
    reverse(g1.begin(), g1.end());
    for (int i = 0; i < m; i++) {
        int u = g1[i].second.first, v = g1[i].second.second;
        if (unite(u, v)) {                                                                                                   
            g2[u].push_back(make_pair(v, g1[i].first));
            g2[v].push_back(make_pair(u, g1[i].first));
        }
    }
    d[0] = inf;
    dfs(1);
    int q;
    cin >> q;
    while(q--) {
        cin >> s >> t;
        int pr = lca(s, t);                   
        cout << min(ans(s, pr), ans(t, pr)) << '\n';
    }         
    return 0;
}

Compilation message (stderr)

plan.cpp: In function 'void dfs(int, int)':
plan.cpp:53:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < g2[v].size(); i++) {
                     ~~^~~~~~~~~~~~~~
plan.cpp: In function 'int main()':
plan.cpp:116:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < g[x].size(); ++i) {
                         ~~^~~~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 13
• Subtask 3: 0 / 12
• Subtask 4: 0 / 19
• Subtask 5: 0 / 46