Submission #909953

#	Time	Username	Problem	Language	Result	Execution time	Memory
909953		nightfal	Simurgh (IOI17_simurgh)	C++14	30 / 100	77 ms	5668 KiB

simurgh

#include <cstdio>
#include <iostream>
#include <cassert>
#include <vector>
#include <cstdlib>
#include <string>
#include <utility>
#include <tuple>

using namespace std;


std::vector<int> find_roads(int n, std::vector<int> u, std::vector<int> v);
int count_common_roads(const std::vector<int>& r);

bool isSubtask1(int n) {return n<=7;}
bool isSubtask2(int n) {return n<=50;}
bool isSubtask3(int n) {return n<=240;}

void dfs3(int startNode, int startEdge, int parent, int now, vector<vector<pair<int,int>>>& edgeL, 
            vector<int>& r2, vector<int>& dNode, vector<vector<int>>& dEdge) {
    dNode[now]=1;
    for(auto& elem: edgeL[now]) {
        int nextNode,nextEdge; tie(nextNode,nextEdge) = elem;
        if (nextNode==parent) continue;
        if (nextNode==startNode) {dEdge[startEdge].push_back(nextEdge); continue;}
        if (!dNode[nextNode]) {
            r2.push_back(nextEdge);
            dfs3(startNode,startEdge,now,nextNode,edgeL,r2,dNode,dEdge);
        }
    }
	return;
}
vector<int> subtask3(int n, std::vector<int>& u, std::vector<int>& v) {
    int m = u.size();
    vector<int> r;
    vector<int> treeEdge(m);

	// Edge list
    vector<vector<pair<int,int>>> edgeL(n);
    for(int i=0; i<m; i++) {
        edgeL[u[i]].push_back(make_pair(v[i],i));
        edgeL[v[i]].push_back(make_pair(u[i],i));
    }
    // printf("Edge list\n");
    // for(int i=0; i<n; i++) {
    //     printf("%d: ", i); for(auto& elem: edgeL[i]) printf("(%d,%d) ", get<0>(elem),get<1>(elem)); printf("\n");
    // }
    // printf("\n");

    for(int startNode=0; startNode<n; startNode++) {
        vector<int> dNode(n); vector<vector<int>> dEdge(m);
        dNode[startNode] = 1;
        vector<int> r2, r2StartEdgeIdx;
        int secondNode,startEdge; 

        for(auto& elem: edgeL[startNode]) {
            tie(secondNode,startEdge) = elem;
            if (dNode[secondNode]) continue;
            r2.push_back(startEdge);
            r2StartEdgeIdx.push_back(r2.size()-1);
            dfs3(startNode,startEdge,startNode,secondNode,edgeL,r2,dNode,dEdge);
            // printf("startNode=%d: dEdge[%d]: ",startNode,startEdge); for(int elem: dEdge[startEdge]) printf("%d ",elem); printf("\n");
            // printf("startNode=%d: r2: ",startNode); for(auto& elem: r2) printf("%d ", elem); printf("\n");
            // printf("startNode=%d: r2StartEdgeIdx: ",startNode); for(auto& elem: r2StartEdgeIdx) printf("%d ", elem); printf("\n");
        }
        // printf("i=%d: dEdge\n",i); 
        // for(int j=0; j<dEdge.size(); j++) {printf("%d: ",j); for(int elem: dEdge[j]) printf("%d ",elem); printf("\n");}

        // return r;
        int defaultCount = count_common_roads(r2);

        for(int startEdgeIdx: r2StartEdgeIdx) {
            vector<int> result;
            // printf("i=%d: r2: ",i); for(auto& elem: r2) printf("%d ", elem); printf("\n");
            int maxValue = defaultCount;
            // printf("maxValue = %d ",maxValue);
            result.push_back(maxValue);
            // printf("startNode=%d: result: ",startNode); for(int elem: result) printf("%d ", elem); printf("\n");

            int startEdge = r2[startEdgeIdx];
            for(int alterativeEdge: dEdge[startEdge]) {
                r2[startEdgeIdx] = alterativeEdge; 
                int temp = count_common_roads(r2);
                // printf("temp=%d ",temp);
                maxValue = max(maxValue,temp);
                result.push_back(temp);
            }
            // printf("startNode=%d: result: ",startNode);for(int elem: result) printf("%d ",elem); printf("\n");
            if(result[0]==maxValue) {treeEdge[startEdge]=1;}
            for(int j=1; j<result.size(); j++) 
                if (result[j] == maxValue) {treeEdge[dEdge[startEdge][j-1]]=1;}
            r2[startEdgeIdx] = startEdge;        
            // printf("\ntreeEdge: "); for(int j=0; j<treeEdge.size(); j++) printf("%d ",treeEdge[j]); printf("\n");
			// printf("\n");
        }
        
    }
    for(int i=0; i<m; i++) if (treeEdge[i]) r.push_back(i);
    // printf("r: ");
    // for(int elem: r) printf("%d ",elem); printf("\n");
    return r;
}

void dfs(int parent, int now, std::vector<int>& visit, std::vector<vector<int>>& edgeL) {
    visit[now]=1;
    for(int elem: edgeL[now])
        if (elem!=parent && !visit[elem])
			dfs(now,elem,visit,edgeL);
	return;
}

bool isTree(std::vector<int>& r, std::vector<int>& u, std::vector<int>& v) {
    int n = r.size()+1;
    std::vector<vector<int>> edgeL(n);
    for(int i=0; i<n-1; i++) {
        int s = u[r[i]], e = v[r[i]];
        edgeL[s].push_back(e);
        edgeL[e].push_back(s);
    }
    vector<int> visit(n,0);
    dfs(-1,u[r[0]],visit,edgeL);
	for(int i=0; i<n; i++)
		if(!visit[i]) return false;
	return true;
}

bool selectEdges(int cnt, int start, std::vector<int>& r, std::vector<int>& u, std::vector<int>& v){
	int n = r.size()+1, m = u.size();
    if (cnt == n-1){
        if(isTree(r,u,v) && count_common_roads(r)== n-1) return true;
        else return false;
    }
    for(int i=start; i<m; i++){
        r[cnt] = i;
        if (selectEdges(cnt+1,i+1,r,u,v)) return true;
    }
    return false;
}

std::vector<int> subtask1(int n, std::vector<int>& u, std::vector<int>& v) {
    std::vector<int> r(n-1), zero(n-1,-1);
    if (selectEdges(0,0,r,u,v)) return r;
    else return zero;
}

std::vector<int> find_roads(int n, std::vector<int> u, std::vector<int> v) {
    return subtask3(n,u,v);
    // if (isSubtask1(n)) 
    return subtask1(n,u,v);
}

Compilation message (stderr)

simurgh.cpp: In function 'std::vector<int> subtask3(int, std::vector<int>&, std::vector<int>&)':
simurgh.cpp:91:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   91 |             for(int j=1; j<result.size(); j++)
      |                          ~^~~~~~~~~~~~~~
simurgh.cpp: In function 'void dfs(int, int, std::vector<int>&, std::vector<std::vector<int> >&)':
simurgh.cpp:107:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  107 |     for(int elem: edgeL[now])
      |     ^~~
simurgh.cpp:110:2: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  110 |  return;
      |  ^~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 17 / 17
• Subtask 3: 0 / 21
• Subtask 4: 0 / 19
• Subtask 5: 0 / 30