Submission #56849

#	Time	Username	Problem	Language	Result	Execution time	Memory
56849		Mamnoon_Siam	Election Campaign (JOI15_election_campaign)	C++17	100 / 100	540 ms	28020 KiB

election_campaign

//#pragma GCC optimize("Ofast,unroll-loops,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include <bits/stdc++.h>
using namespace std;

#define debug(s) cout<< #s <<" = "<< s <<endl
#define all(v) (v).begin(), (v).end()
#define KeepUnique(v) (v).erase( unique(all(v)), v.end() )
#define MEMSET(a,val) memset(a, val, sizeof a)
#define PB push_back
#define endl '\n'
typedef long long ll;

inline int myrand(int l, int r) {
	int ret = rand(); ret <<= 15; ret ^= rand();
	if(ret < 0) ret = -ret; ret %= (r-l+1); ret += l;
	return ret;
}
template <typename F, typename S>
ostream& operator << (ostream& os, const pair< F, S>& p) {
    return os<<"(" <<p.first<<", "<<p.second<<")"; }

typedef pair<int, int> ii;
template<typename T> using min_pq =
	priority_queue<T, vector<T>, greater<T> >;

//int dx[] = {-1, +0, +1, +0};
//int dy[] = {+0, +1, +0, -1};

const int maxn = 100005;

int n, m;
vector<int> g[maxn], paths[maxn], A, B, C;
int t[18][maxn], dp[maxn], sz[maxn], where[maxn], lvl[maxn], tym = 0;
ll S[maxn];

int dfs(int u, int par) {
	sz[u] = 1;
	where[u] = ++tym;
	t[0][u] = par;
	lvl[u] = par == -1 ? 0 : lvl[par] + 1;
	for(int v : g[u]) {
		if(par - v) {
			dfs(v, u);
			sz[u] += sz[v];
		}
	}
}

int __lca(int u, int v) {
	if(lvl[u] > lvl[v]) swap(u, v);
	int d = lvl[v] - lvl[u];
	for(int i = 16; i >= 0; i--) {
		if(d & (1 << i)) {
			v = t[i][v];
		}
	}
	if(u == v) return u;
	for(int i = 16; i >= 0; i--) {
		if(t[i][u] != t[i][v]) {
			u = t[i][u];
			v = t[i][v];
		}
	} return t[0][u];
}

void update(int u, int val) {
	int l = where[u], r = where[u] + sz[u];
	for(; l <= n; l += l & -l) S[l] += val;
	for(; r <= n; r += r & -r) S[r] -= val;
}
int query(int u, int ret = 0) {
	for(int p = where[u]; p > 0; p -= p & -p)
		ret += S[p];
	return ret;
}
int value(int u) {
	return query(u) - (u != 1 ? query(t[0][u]) : 0);
}
int pathcost(int i) { // query path S[u] sum
	int u = A[i], v = B[i];
	int lca = __lca(u, v);
	return query(u) + query(v) - query(lca) - (lca == 1 ? 0 : query(t[0][lca]));
}

void prep(int u, int par) {
	for(int v : g[u]) {
		if(v - par) {
			prep(v, u);
			update(u, dp[v]);
		}
	}
	dp[u] = value(u);
	for(int p : paths[u]) {
		int ret = C[p] + pathcost(p);
		dp[u] = max(dp[u], ret);
	}
	update(u, -dp[u]);
}

int32_t main () {
	// freopen("in", "r", stdin);
	scanf("%d", &n);
	for(int i = 1; i < n; i++) {
		int u, v; scanf("%d %d", &u, &v);
		g[u].push_back(v);
		g[v].push_back(u);
	}
	MEMSET(t, -1);
	dfs(1, -1);
	for(int p = 1; p <= 16; p++) {
		for(int i = 1; i <= n; i++) {
			int mid = t[p - 1][i];
			if(mid != -1) t[p][i] = t[p - 1][mid];
		}
	}
	scanf("%d", &m);
	A.resize(m), B.resize(m), C.resize(m);
	for(int i = 0; i < m; i++) {
		scanf("%d %d %d", &A[i], &B[i], &C[i]);
		paths[__lca(A[i], B[i])].push_back(i);
	}
	prep(1, -1);
	printf("%d\n", dp[1]);
}

Compilation message (stderr)

election_campaign.cpp: In function 'int myrand(int, int)':
election_campaign.cpp:17:2: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
  if(ret < 0) ret = -ret; ret %= (r-l+1); ret += l;
  ^~
election_campaign.cpp:17:26: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
  if(ret < 0) ret = -ret; ret %= (r-l+1); ret += l;
                          ^~~
election_campaign.cpp: In function 'int dfs(int, int)':
election_campaign.cpp:49:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
election_campaign.cpp: In function 'int32_t main()':
election_campaign.cpp:104:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ~~~~~^~~~~~~~~~
election_campaign.cpp:106:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int u, v; scanf("%d %d", &u, &v);
             ~~~~~^~~~~~~~~~~~~~~~~
election_campaign.cpp:118:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &m);
  ~~~~~^~~~~~~~~~
election_campaign.cpp:121:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d %d", &A[i], &B[i], &C[i]);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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