Submission #853582

#	Time	Username	Problem	Language	Result	Execution time	Memory
853582		ntkphong	Connecting Supertrees (IOI20_supertrees)	C++14	11 / 100	169 ms	24148 KiB

supertrees

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

vector<int> lab;

int get_root(int u) {
    return lab[u] == u ? u : lab[u] = get_root(lab[u]);
}

bool unite(int u, int v) {
    u = get_root(u);
    v = get_root(v);
    
    if(u == v) return false;
    lab[v] = u;
    
    return true;
}

int construct(vector<vector<int>> p) {
	int n = p.size();
    
    lab.resize(n);
    for(int i = 0; i < n; i ++) lab[i] = i;
    
    vector<int> mark(n, 0);
    vector<vector<int>> answer(n, vector<int> (n, 0));	
    
	for (int i = 0; i < n; i ++) {
	    for(int j = 0; j < n; j ++) {
	        if(get_root(i) == get_root(j) || p[i][j] != 1) continue ;
	        
	        answer[i][j] = answer[j][i] = 1;
            unite(i, j);
	    }
	}
	
	for(int i = 0; i < n; i ++) {
        if(get_root(i) != i) continue ;
        
        vector<int> row;
        
        for(int j = 0; j < n; j ++) {
            if(p[i][j] != 2) continue ;
            if(mark[j]) return 0;
            row.push_back(j);
        }
        
        if(row.empty()) continue ; 
        
        int root = i;
        int k = i;
        int cnt = 1;
        
        for(int j = 0; j < row.size(); j ++) {
            if(unite(k, row[j])) {
                answer[row[j]][k] = 1;
                answer[k][row[j]] = 1;
                k = row[j];
                cnt ++ ;
            }
        }
        
        answer[root][k] = 1;
        answer[k][root] = 1;
        
        for(int j = 0; j < n; j ++) {
            if(get_root(i) == get_root(j)) {
                mark[j] = 1;
            }
        }
        
        for(int x : row) {
            for(int y : row) {
                if(x == y) continue ;
                if(p[x][y] != 2) return 0;
            }
        }
          
        if(cnt <= 2) return 0;
	}
	
	for(int i = 0; i < n; i ++) {
        if(get_root(i) != i) continue ;
        
        vector<int> row;
        
        for(int j = 0; j < n; j ++) {
            if(p[i][j] != 3) continue ;
            if(mark[j]) return 0;
            row.push_back(j);
        }
        
        if(row.empty()) continue ; 
        
        int root = i;
        int k = i, prev_k = 0;
        int cnt = 1;
        
        for(int j = 0; j < row.size(); j ++) {
            if(unite(k, row[j])) {
                answer[j][k] = 1;
                answer[k][j] = 1;
                
                prev_k = k;
                k = j;
                cnt ++ ;
            }
        }
        
        answer[root][k] = 1;
        answer[k][root] = 1;
        
        answer[root][prev_k] = 1;
        answer[prev_k][root] = 1;
        
        
        for(int j = 0; j < n; j ++) {
            if(get_root(i) == get_root(j)) {
                mark[j] = 1;
            }
        }
        
        for(int x : row) {
            for(int y : row) {
                if(x == y) continue ;
                if(p[x][y] != 2) return 0;
            }
        }
        
        if(cnt <= 3) return 0;
	}
	
  	build(answer);
	return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:56:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   56 |         for(int j = 0; j < row.size(); j ++) {
      |                        ~~^~~~~~~~~~~~
supertrees.cpp:101:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |         for(int j = 0; j < row.size(); j ++) {
      |                        ~~^~~~~~~~~~~~

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