Submission #475785

#	Time	Username	Problem	Language	Result	Execution time	Memory
475785		maomao90	Aesthetic (NOI20_aesthetic)	C++17	35 / 100	1951 ms	40352 KiB

Aesthetic

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

template <class T>
inline bool mnto(T& a, T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}
#define REP(i, s, e) for (int i = s; i < e; i++)
#define RREP(i, s, e) for (int i = s; i >= e; i--)
typedef long long ll;
typedef long double ld;
#define MP make_pair
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
#define MT make_tuple
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;

#ifdef DEBUG
#define debug(args...) printf(args)
#else
#define debug(args...)
#endif

#define INF 1000000005
#define LINF 1000000000000000005
#define MOD 1000000007
#define MAXN 300005

struct edge {
	int v, w, p;
};

int n, m;
vector<edge> adj[MAXN];
int a[MAXN], b[MAXN], w[MAXN], p[MAXN];
ll base;

priority_queue<pll, vector<pll>, greater<pll>> pq;
ll d1[MAXN], dn[MAXN];
void dij(int s, ll* d) {
	REP (i, 1, n + 1) {
		d[i] = LINF;
	}
	d[s] = 0;
	pq.push(MP(0, s));
	while (!pq.empty()) {
		auto [ud, u] = pq.top(); pq.pop();
		if (ud != d[u]) continue;
		for (edge e : adj[u]) {
			if (mnto(d[e.v], ud + e.w)) {
				pq.push(MP(d[e.v], e.v));
			}
		}
	}
}

ll x;
bool res;
int pre[MAXN], top[MAXN], ptr;
void dfs(int u, int p) {
	pre[u] = top[u] = ptr++;
	for (edge e : adj[u]) {
		if (e.v == p) continue;
		if (min(d1[u] + dn[e.v], d1[e.v] + dn[u]) + e.w > x + base) continue;
		if (pre[e.v] == -1) {
			dfs(e.v, u);
			mnto(top[u], top[e.v]);
			if (top[e.v] > pre[u]) {
				if ((min(d1[u] + dn[e.v], d1[e.v] + dn[u])
					   	+ e.w + e.p > x + base) && 
						pre[n] != -1 && 
						pre[n] >= pre[e.v])	{
					res = 1;
				}
			}
		} else {
			mnto(top[u], pre[e.v]);
		}
	}
}

bool isPos(ll x) {
	ptr = 0;
	::x = x;
	res = 0;
	memset(pre, -1, sizeof pre);
	dfs(1, -1);
	return res;
}

int main() {
	scanf("%d%d", &n, &m);
	REP (i, 0, m) {
		scanf("%d%d%d", &a[i], &b[i], &w[i]);
	}
	int mx = 0;
	RREP (i, m - 1, 0) {
		p[i] = mx;
		mxto(mx, w[i]);
	}
	REP (i, 0, m) {
		adj[a[i]].pb({b[i], w[i], p[i]});
		adj[b[i]].pb({a[i], w[i], p[i]});
	}
	dij(1, d1);
	dij(n, dn);
	base = d1[n];
	ll lo = 0, hi = INF, mid;
	while (lo < hi) {
		mid = lo + hi + 1 >> 1;
		if (isPos(mid)) {
			lo = mid;
		} else {
			hi = mid - 1;
		}
	}
	printf("%lld\n", base + lo + 1);
	return 0;
}

Compilation message (stderr)

Aesthetic.cpp: In function 'int main()':
Aesthetic.cpp:117:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  117 |   mid = lo + hi + 1 >> 1;
      |         ~~~~~~~~^~~
Aesthetic.cpp:99:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   99 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
Aesthetic.cpp:101:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |   scanf("%d%d%d", &a[i], &b[i], &w[i]);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 7 / 7
• Subtask 4: 15 / 15
• Subtask 5: 0 / 16
• Subtask 6: 0 / 22
• Subtask 7: 0 / 27