Submission #786977

#	Time	Username	Problem	Language	Result	Execution time	Memory
786977		acatmeowmeow	Connecting Supertrees (IOI20_supertrees)	C++14	21 / 100	167 ms	24268 KiB

supertrees

#include "supertrees.h"
#include <bits/stdc++.h>

using namespace std;

const int N = 1e3;
int par[N + 5], sz[N + 5];
vector<int> ls[N + 5];
int vertex[N + 5];
bool vis[N + 5];

int find(int x) { return x == par[x] ? x : find(par[x]); }

bool same(int x, int y) { return find(x) == find(y); }

void unite(int x, int y) { 
	x = find(x), y = find(y);
	if (sz[x] < sz[y]) swap(x, y);
	sz[x] += sz[y], par[y] = x;
}

int construct(std::vector<std::vector<int>> p) {
	int n = p.size();
	
	// check connectivity
	for (int i = 0; i < n; i++) par[i] = i, sz[i] = 1;	
	for (int i = 0; i < n; i++) {
		for (int j = i + 1; j < n; j++) {
			if (p[i][j] && !same(i, j)) unite(i, j);
		}
	}
	for (int i = 0; i < n; i++) {
		for (int j = i + 1; j < n; j++) {
			if (!p[i][j] && same(i, j)) return 0;
		}
	}
	
	for (int i = 0; i < n; i++) ls[find(i)].push_back(i);

	for (int i = 0; i < n; i++) vertex[i] = -1;	
	vector<vector<int>> b(n, vector<int>(n));	
	for (auto&arr : ls) {
		if (arr.empty()) continue;
		int sz = arr.size(), hasTwo = false, hasThree = false;
		for (int i = 0; i < sz; i++){
			for (int j = i + 1; j < sz; j++) {
				int u = arr[i], v = arr[j];
				hasTwo |= p[u][v] == 2, hasThree |= p[u][v] == 3;
			}
		}
		if (hasTwo && hasThree) return 0;
		if (!hasTwo && !hasThree) {
			for (int i = 0; i + 1 < sz; i++){
				int u = arr[i], v = arr[i + 1];
				b[u][v] = b[v][u] = 1;
			}
			continue;
		}
		vector<int> loop;
		for (int i = 0, flag = 0; !flag && i < sz; i++) {
			for (int j = i + 1; j < sz; j++) {
				int u = arr[i], v = arr[j];
				if (p[u][v] >= 2) {
					loop.push_back(u), loop.push_back(v);
					vertex[u] = -1, vertex[v] = -1;
					flag = true;
					break;
				}
			}
		}
		for (int i = 0; i < sz; i++) {
			int valid = 1, u = arr[i];
			for (auto&v : loop) valid &= u != v && p[u][v] >= 2;	
			if (valid) loop.push_back(i);
		}

		if (hasTwo && loop.size() <= 2) return 0;
		else if (hasThree && loop.size() <= 3) return 0;

		for (int i = 0; i < loop.size(); i++) {
			int u = loop[i], v = loop[(i + 1) % loop.size()];
			b[u][v] = b[v][u] = 1;
		}
		if (hasThree) b[loop[0]][loop[2]] = b[loop[2]][loop[0]] = 1;
		queue<int> q;
		for (auto&v : loop) q.push(v), vis[v] = true;
		while (q.size()) {
			int u = q.front(); q.pop();
			for (int i = 0; i < sz; i++) {
				int v = arr[i];
				if (v == u || vis[v] || p[v][u] != 1) continue;
				vis[v] = true;
				if (vertex[u] == -1) vertex[v] = u;
				else vertex[v] = vertex[u];
				q.push(v);
				b[u][v] = b[v][u] = 1;
			}
		}
		for (int i = 0; i + 1 < sz; i++) {
			int u = arr[i], v = arr[i + 1];
			if (p[u][v] > 1 && vertex[u] != -1 && vertex[v] != -1 && vertex[u] != vertex[v]) return 0;
		}
	}
	build(b);
	return 1;
}

/*static int n;
static std::vector<std::vector<int>> p;
static std::vector<std::vector<int>> b;
static bool called = false;

static void check(bool cond, std::string message) {
    if (!cond) {
        printf("%s\n", message.c_str());
        fclose(stdout);
        exit(0);
    }
}

void build(std::vector<std::vector<int>> _b) {
    check(!called, "build is called more than once");
    called = true;
    check((int)_b.size() == n, "Invalid number of rows in b");
    for (int i = 0; i < n; i++) {
        check((int)_b[i].size() == n, "Invalid number of columns in b");
    }
    b = _b;
}

int main() {
    //assert(scanf("%d", &n) == 1);
	cin >> n;

    p.resize(n);
    for (int i = 0; i < n; i++) {
        p[i].resize(n);
    }

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            //assert(scanf("%d", &p[i][j]) == 1);
			cin >> p[i][j];
        }
    }
    //fclose(stdin);

    int possible = construct(p);

    check(possible == 0 || possible == 1, "Invalid return value of construct");
    if (possible == 1) {
        check(called, "construct returned 1 without calling build");
    } else {
        check(!called, "construct called build but returned 0");
    }

    printf("%d\n", possible);
    if (possible == 1) {
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                if (j) {
                    printf(" ");
                }
                printf("%d", b[i][j]);
            }
            printf("\n");
        }
    }
   // fclose(stdout);
}*/

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:80:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   80 |   for (int i = 0; i < loop.size(); i++) {
      |                   ~~^~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 10 / 10
• Subtask 3: 0 / 19
• Subtask 4: 0 / 35
• Subtask 5: 0 / 21
• Subtask 6: 0 / 4