Submission #143160

#	Time	Username	Problem	Language	Result	Execution time	Memory
143160		Ruxandra985	Pipes (CEOI15_pipes)	C++14	100 / 100	1697 ms	14660 KiB

pipes

#include <cstdio>
#include <vector>
#include <algorithm>
#include <cstring>
#define DIMN 100005
using namespace std;
int fth[DIMN],fth2[DIMN],sum[DIMN];
vector <int> v[DIMN];
int lvl[DIMN];
bool f[DIMN];
int d[18][DIMN];
int logg[DIMN];
int elem;
int root (int nod){
    int init = nod,aux;
    while (fth[nod]>0){
        nod = fth[nod];
    }
    while (fth[init]>0){ /// amortizare
        aux = fth[init];
        fth[init] = nod;
        init = aux;
    }
    return nod;
}
int root2 (int nod){
    int init = nod,aux;
    while (fth2[nod]>0){
        nod = fth2[nod];
    }
    while (fth2[init]>0){ /// amortizare
        aux = fth2[init];
        fth2[init] = nod;
        init = aux;
    }
    return nod;
}
void dfs (int nod,int tata){
    int i,vecin;
    f[nod] = 1;
    for (i=0;i<v[nod].size();i++){
        vecin = v[nod][i];
        if (vecin!=tata){
            dfs(vecin , nod);
            sum[nod]+=sum[vecin];
            if (!sum[vecin]){
                printf ("%d %d\n",nod,vecin);
            }
        }
    }
}
void dfs_lca (int nod,int niv,int tt){
    int i,vecin;
    d[0][nod] = tt;
    lvl[nod] = niv;
    f[nod] = 1;
    for (i=0;i<v[nod].size();i++){
        vecin=v[nod][i];
        if (vecin!=tt){
            dfs_lca(vecin,niv+1,nod);
        }
    }
}

int kth (int nod , int k){
    while (k && nod!=0){
        nod=d[logg[k]][nod];
        k=k-(1<<logg[k]);
    }
    return nod;
}

int query (int x,int y){
    int st,dr,mid;
    if (lvl[x] < lvl[y])
        swap(x,y);
    if (lvl[x] > lvl[y])
        x = kth( x , lvl[x] - lvl[y] );
    st = 0;
    dr = lvl[x]-1;
    while (st <= dr){
        mid = (st + dr)/2;
        if (kth(x,mid) == kth(y,mid))
            dr = mid - 1;
        else st = mid + 1;
    }
    return kth(x,st);
}
int main()
{
    //freopen ("a.in" , "r" , stdin);
    int n,m,i,x,y,rx,ry;
    scanf ("%d%d",&n,&m);
    for (i=1;i<=n;i++)
        fth[i] = fth2[i] = -1;
    for (i=1;i<=m;i++){
        scanf ("%d%d",&x,&y);
        rx = root(x);
        ry = root(y);
        if (rx != ry){ /// sunt in cc diferite
            v[x].push_back(y);
            v[y].push_back(x); /// mai multi arbori
            if (fth[rx] < fth[ry]){
                fth[rx]+=fth[ry];
                fth[ry] = rx;
            }
            else {
                fth[ry]+=fth[rx];
                fth[rx] = ry;
            }
        }
        else {
            rx = root2(x);
            ry = root2(y);
            if (rx!=ry){ /// unesti in fth2
                if (fth2[rx] < fth2[ry]){
                    fth2[rx]+=fth2[ry];
                    fth2[ry] = rx;
                }
                else {
                    fth2[ry]+=fth2[rx];
                    fth2[rx] = ry;
                }
            }
        }
    }

    /// faci lca cu stramosi ca sa economisesti memorie

    for (i=1;i<=n;i++){
        if (!f[i]){
            dfs_lca (i,1,0);
        }
    }

    memset ( f, 0 ,sizeof(f) );


    for (i=2;i<=n;i++)
        logg[i] = logg[i/2] + 1;

    for (int powe=1;powe<=logg[n];powe++){
        for (i=1;i <= n;i++){
            d[powe][i] = d[powe-1][d[powe-1][i]];
        }
    }

    for (i=1;i<=n;i++){ /// daca ai o muchie in fth2 , stergi din fth
        if (fth2[i]>0){
            int lca = query (i , fth2[i]);
            sum[i]++;
            sum[fth2[i]]++;
            sum[lca]-=2;
        }
    }
    for (i=1;i<=n;i++){
        if (!f[i])
            dfs(i,0);
    }
    return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'void dfs(int, int)':
pipes.cpp:41:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i=0;i<v[nod].size();i++){
              ~^~~~~~~~~~~~~~
pipes.cpp: In function 'void dfs_lca(int, int, int)':
pipes.cpp:57:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i=0;i<v[nod].size();i++){
              ~^~~~~~~~~~~~~~
pipes.cpp: In function 'int main()':
pipes.cpp:93:11: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf ("%d%d",&n,&m);
     ~~~~~~^~~~~~~~~~~~~~
pipes.cpp:97:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf ("%d%d",&x,&y);
         ~~~~~~^~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10