Submission #66134

#	Time	Username	Problem	Language	Result	Execution time	Memory
66134		kingpig9	Evacuation plan (IZhO18_plan)	C++11	100 / 100	786 ms	43912 KiB

plan

#include <bits/stdc++.h>
 
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int MAXN = 1e5 + 10;
const int MAXLG = 17;
const int INF = 1e8;
 
#define debug(...) fprintf(stderr, __VA_ARGS__)
#define all(v) (v).begin(), (v).end()
#define fi first
#define se second
#define fillchar(a, s) memset((a), (s), sizeof(a))
 
int N, M;
vector<pii> adj[MAXN];
 
struct union_find {
	int par[MAXN];
 
	void reset() {
		for (int i = 0; i < N; i++) {
			par[i] = i;
		}
	}
 
	int find (int x) {
		return x == par[x] ? x : par[x] = find(par[x]);
	}
 
	bool merge (int x, int y) {
		x = find(x);
		y = find(y);
		if (x == y) {
			return false;
		}
		par[x] = y;
		return true;
	}
} uf;
 
int K, G[MAXN];
int dist[MAXN];
bool vis[MAXN];
 
int Q;
 
//code for dijkstra
void dijkstra() {
	priority_queue<pii, vector<pii>, greater<pii>> pq;
	for (int i = 0; i < N; i++) {
		dist[i] = INF;
	}
 
	for (int i = 0; i < K; i++) {
		int x = G[i];
		dist[x] = 0;
		pq.push({0, x});
	}
 
	while (!pq.empty()) {
		int u = pq.top().se, w = pq.top().fi;
		pq.pop();
		if (vis[u]) {
			continue;
		}
 
		vis[u] = true;
		for (pii e : adj[u]) {
			int v = e.se;
			int nw = e.fi + w;
 
			if (dist[v] > nw) {
				dist[v] = nw;
				pq.push({nw, v});
			}
		}
	}
 
 	/*
	for (int i = 0; i < N; i++) {
		debug("dist[%d] = %d\n", i, dist[i]);
	}
	*/
}

vector<pii> tree[MAXN];
int par[MAXN][MAXLG];
int mnw[MAXN][MAXLG];
int depth[MAXN];

void dfs (int x) {
	for (pii e : tree[x]) {
		int w = e.fi;
		int y = e.se;
		for (auto it = tree[y].begin(); ; it++) {
			if (it->se == x) {
				tree[y].erase(it);
				break;
			}
		}

		depth[y] = depth[x] + 1;
		par[y][0] = x;
		mnw[y][0] = w;
		for (int i = 1; i < MAXLG; i++) {
			int pp = par[par[y][i - 1]][i - 1];
			if (pp == -1) {
				break;
			}
			par[y][i] = pp;
			mnw[y][i] = min(mnw[y][i - 1], mnw[par[y][i - 1]][i - 1]);
		}

		dfs(y);
	}
}

int getpar (int x, int d) {
	for (int i = 0; d; i++, d >>= 1) {
		if (d & 1) {
			x = par[x][i];
		}
	}
	return x;
}

int lca (int x, int y) {
	if (depth[x] < depth[y]) {
		swap(x, y);
	}
	x = getpar(x, depth[x] - depth[y]);
	if (x == y) {
		return x;
	}

	for (int i = MAXLG - 1; i >= 0; i--) {
		if (par[x][i] != par[y][i]) {
			x = par[x][i];
			y = par[y][i];
		}
	}
	return par[x][0];
}

int minjump (int x, int d) {
	if (d == 0) {
		return INT_MAX;
	}

	int res = INT_MAX;
	for (int i = 0; d; i++, d >>= 1) {
		if (d & 1) {
			res = min(res, mnw[x][i]);
			x = par[x][i];
		}
	}
	return res;
}

int getmin (int x, int y) {
	int c = lca(x, y);
	return min(minjump(x, depth[x] - depth[c]), minjump(y, depth[y] - depth[c]));
}

int main() {
	scanf("%d %d", &N, &M);
	for (int i = 0; i < M; i++) {
		int a, b, w;
		scanf("%d %d %d", &a, &b, &w);
		a--;
		b--;
		adj[a].push_back({w, b});
		adj[b].push_back({w, a});
	}
 
	scanf("%d", &K);
	for (int i = 0; i < K; i++) {
		scanf("%d", &G[i]);
		G[i]--;
	}
 
	dijkstra();

	vector<array<int, 3>> edges;
	for (int i = 0; i < N; i++) {
		for (pii e : adj[i]) {
			int j = e.se;
			//min bottleneck path
			if (i < j) {
				edges.push_back({min(dist[i], dist[j]), i, j});
			}
		}
	}

	sort(edges.rbegin(), edges.rend());
	uf.reset();
 	for (auto e : edges) {
		if (uf.merge(e[1], e[2])) {
			//debug("TREE EDGE %d %d %d\n", e[1], e[2], e[0]);
			tree[e[1]].push_back({e[0], e[2]});
			tree[e[2]].push_back({e[0], e[1]});
		}
	}
	fillchar(par, -1);
	dfs(0);
 
	scanf("%d", &Q);
	for (int i = 0; i < Q; i++) {
		int s, t;
		scanf("%d %d", &s, &t);
		printf("%d\n", getmin(s - 1, t - 1));
	}
}

Compilation message (stderr)

plan.cpp: In function 'int main()':
plan.cpp:168:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &N, &M);
  ~~~~~^~~~~~~~~~~~~~~~~
plan.cpp:171:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d %d", &a, &b, &w);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
plan.cpp:178:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &K);
  ~~~~~^~~~~~~~~~
plan.cpp:180:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &G[i]);
   ~~~~~^~~~~~~~~~~~~
plan.cpp:209:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &Q);
  ~~~~~^~~~~~~~~~
plan.cpp:212:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &s, &t);
   ~~~~~^~~~~~~~~~~~~~~~~

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