Submission #63828885

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Source Code Expand

// Problem: G - Maximize Distance
// Contest: AtCoder - OMRON Corporation Programming Contest 2025 (AtCoder Beginner Contest 397)
// URL: https://atcoder.jp/contests/abc397/tasks/abc397_g
// Memory Limit: 1024 MB
// Time Limit: 2000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>
#define pb emplace_back
#define fst first
#define scd second
#define mkp make_pair
#define uint unsigned
#define mems(a, x) memset((a), (x), sizeof(a))

using namespace std;
typedef long long ll;
typedef double db;
typedef unsigned long long ull;
typedef long double ldb;
typedef pair<int, int> pii;

const int maxn = 10050;
const int inf = 0x3f3f3f3f;

int n, m, K, hd[maxn], len, id[maxn];
pii a[maxn];
bool vis[maxn], mk[maxn];

struct edge {
	int to, cap, flow, next;
} edges[maxn];

inline void add_edge(int u, int v, int c, int f) {
	edges[++len].to = v;
	edges[len].next = hd[u];
	edges[len].cap = c;
	edges[len].flow = f;
	hd[u] = len;
}

struct Dinic {
	int d[maxn], cur[maxn];
	bool vis[maxn];
	
	inline void add(int u, int v, int c) {
		add_edge(u, v, c, 0);
		add_edge(v, u, 0, 0);
	}
	
	inline bool bfs() {
		queue<int> q;
		for (int i = 1; i <= n; ++i) {
			vis[i] = 0;
			d[i] = -1;
		}
		d[1] = 0;
		vis[1] = 1;
		q.push(1);
		while (q.size()) {
			int u = q.front();
			q.pop();
			for (int i = hd[u]; i; i = edges[i].next) {
				edge &e = edges[i];
				if (!vis[e.to] && e.cap > e.flow) {
					vis[e.to] = 1;
					d[e.to] = d[u] + 1;
					q.push(e.to);
				}
			}
		}
		return vis[n];
	}
	
	int dfs(int u, int a) {
		if (u == n || !a) {
			return a;
		}
		int flow = 0, f;
		for (int &i = cur[u]; i; i = edges[i].next) {
			edge &e = edges[i];
			if (d[e.to] == d[u] + 1 && (f = dfs(e.to, min(a, e.cap - e.flow))) > 0) {
				e.flow += f;
				edges[i ^ 1].flow -= f;
				flow += f;
				a -= f;
				if (!a) {
					break;
				}
			}
		}
		return flow;
	}
	
	inline int solve() {
		int flow = 0;
		while (bfs()) {
			for (int i = 1; i <= n; ++i) {
				cur[i] = hd[i];
			}
			flow += dfs(1, inf);
		}
		return flow;
	}
} solver;

void dfs(int u) {
	mk[u] = 1;
	for (int i = hd[u]; i; i = edges[i].next) {
		edge &e = edges[i];
		if (!mk[e.to] && e.cap > e.flow) {
			dfs(e.to);
		}
	}
}

void solve() {
	scanf("%d%d%d", &n, &m, &K);
	for (int i = 1; i <= m; ++i) {
		scanf("%d%d", &a[i].fst, &a[i].scd);
	}
	int ans = 0;
	while (1) {
		mems(hd, 0);
		len = 1;
		for (int i = 1; i <= m; ++i) {
			solver.add(a[i].fst, a[i].scd, vis[i] ? 1e4 : 1);
			id[i] = len - 1;
		}
		int t = solver.solve();
		if (t > K) {
			break;
		}
		K -= t;
		++ans;
		mems(mk, 0);
		dfs(1);
		for (int i = 1; i <= m; ++i) {
			if (mk[a[i].fst] && !mk[a[i].scd] && edges[id[i]].cap == edges[id[i]].flow) {
				vis[i] = 1;
			}
		}
	}
	printf("%d\n", ans);
}

int main() {
	int T = 1;
	// scanf("%d", &T);
	while (T--) {
		solve();
	}
	return 0;
}

Submission Info

Compile Error

Main.cpp: In function ‘void solve()’:
Main.cpp:119:14: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  119 |         scanf("%d%d%d", &n, &m, &K);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~
Main.cpp:121:22: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  121 |                 scanf("%d%d", &a[i].fst, &a[i].scd);
      |                 ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Judge Result