Submission #304871

#	Time	Username	Problem	Language	Result	Execution time	Memory
304871		daveeed	Connecting Supertrees (IOI20_supertrees)	C++17	40 / 100	264 ms	22264 KiB

supertrees

#include "supertrees.h"
#include <vector>

const int MAXN = 1000;

int parent[MAXN], sz[MAXN], comp[MAXN], c;

int find(int p){
    while (p != parent[p])
        p = parent[p];
    return p;
}

void merge(int p, int q) {
    int rootP = find(p);
    int rootQ = find(q);
    if (rootP == rootQ) return;
    if (sz[rootP] < sz[rootQ]) {
        parent[rootP] = rootQ;
        sz[rootQ] += sz[rootP];
    }
    else {
        parent[rootQ] = rootP;
        sz[rootP] += sz[rootQ];
    }
}

int construct(std::vector<std::vector<int> > p) {
	int n = p.size();
	std::vector<std::vector<int> > answer;
	for (int i = 0; i < n; i++) {
		std::vector<int> row;
		row.resize(n);
		answer.push_back(row);
	}

    for(int i = 0; i < n; i++){
        parent[i] = i;
    }

    bool isOne = false;
    bool isTwo = false;

    for(int i = 0; i < n; i++){
        for(int j = i + 1; j < n; j++){
            if(p[i][j])
                merge(i, j);
            if(p[i][j] == 1)
                isOne = true;
            if(p[i][j] == 2)
                isTwo = true;
        }
    }

    for(int i = 0; i < n; i++){
        for(int j = i + 1; j < n; j++){
            if(find(i) == find(j) && !p[i][j])
                return 0;
        }
    }
    if(isOne && isTwo){
        for(int i = 0; i < n; i++){
            int r = find(i);
            if(r == i){
                std::vector<int> inComp;
                std::vector<int> inCircle;
                for(int j = 0; j < n; j++){
                    if(find(j) == r){
                        inComp.push_back(j);
                    }
                }
                int start = -1;
                int prev = -1;
                for(int j = 0; j < inComp.size(); j++) if(comp[inComp[j]] == 0){
                    comp[inComp[j]] = ++c;
                    for(int k = j + 1; k < inComp.size(); k++) if(comp[inComp[k]] == 0){
                        if(p[inComp[j]][inComp[k]] == 1){
                            comp[inComp[k]] = comp[inComp[j]];
                            answer[inComp[j]][inComp[k]] = 1;
                            answer[inComp[k]][inComp[j]] = 1;
                        }
                    }
                    if(start == -1){
                        start = inComp[j];
                        prev = inComp[j];
                    }
                    else{
                        answer[prev][inComp[j]] = 1;
                        answer[inComp[j]][prev] = 1;
                        prev = inComp[j];
                    }
                }
                answer[prev][start] = 1;
                answer[start][prev] = 1;
                if(c == 2)
                    return 0;
            }
        }
    }
    else if(isOne){
        for(int i = 0; i < n; i++){
            int r = find(i);
            if(r != i){
                answer[r][i] = 1;
                answer[i][r] = 1;
            }
        }
    }
    else if(isTwo){
        for(int i = 0; i < n; i++){
            int r = find(i);
            if(r == i){
                int prev = -1;
                int count = 0;
                int start = -1;
                for(int j = 0; j < n; j++){
                    if(find(j) == r){
                        count++;
                        if(prev == -1){
                            prev = j;
                            start = j;
                        }
                        else{
                            answer[prev][j] = 1;
                            answer[j][prev] = 1;
                            prev = j;
                        }
                    }
                }
                if(count == 1){
                    continue;
                }
                if(count == 2){
                    return 0;
                }
                answer[prev][start] = 1;
                answer[start][prev] = 1; 
            }
        }
    }

	build(answer);
	return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:74:34: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   74 |                 for(int j = 0; j < inComp.size(); j++) if(comp[inComp[j]] == 0){
      |                                ~~^~~~~~~~~~~~~~~
supertrees.cpp:76:42: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   76 |                     for(int k = j + 1; k < inComp.size(); k++) if(comp[inComp[k]] == 0){
      |                                        ~~^~~~~~~~~~~~~~~

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