hihocoder#1181 (Euler path)

Time limit: 10000ms single point time limit: 1000ms memory limit: 256MB description

In the last back small hi and small ho control the protagonist gathered scattered on the wooden bridge props, these props are actually a piece of dominoes.

The protagonist continued to move forward, a stone bridge appeared in front of the stone bridge at the end of a fire wall, it seems unable to pass.

Little Hi noticed that there was a small piece of paper at the bridge, so the controlling protagonist picked up the paper, and saw it read:

The flame wall can be closed by placing the M-block dominoes in the concave of the stone bridge. Remember that dominoes need the same number to connect. --by unknown adventurer.

Small hi and Small ho opened the main character of the props bar, found that the protagonist happens to have M fast Domino.

Small ho: That means to put all the dominoes in the groove to close the flame wall, what does the number mean?

Little hi: You see, each piece of dominoes has a number at each end, presumably only when the number is the same, can be placed together, such as:

Little ho: So, let's see if we can connect all the dominoes together.

Hint: Fleury algorithm to find Euler path

Input

Line 1th: 2 positive integers, n,m. Indicates the maximum number and number of dominoes that appear on the dominoes, respectively. 1≤n≤1,000,1≤m≤5,000

2nd.. M+1 lines: 2 integers per line, u,v. Line I+1 represents the number (U,V) at both ends of the block I, 1≤u,v≤n

Output

Line 1th: m+1 numbers, indicating the number after the end of a domino

For example, the status of the Domino connection is (1,5) (5,3) (3,2) (2,4) (4,3), then output "1 5 3 2 4 3"

You can output any set of legitimate solutions.

Sample input

5 53 53 24 23 45 1

Sample output

1 5 3 4 2 3
Note: This topic must be traversed from node 1th to AC. When the non-direction graph is deleted, the forward edge associated with the u,v is deleted.
The Euler path of the non-direction graph is conveniently used in code 1, and it is convenient to use the forward direction to calculate Euler path.

#include <cstdio>#include<cstring>#include<vector>using namespacestd;Const intmaxn=1005;structedge{intu,v; intGetto (intu) {if(u== This-&GT;U)returnv; Else return  This-u; }}es[5005];intn,m;intdeg[maxn],vis[5005];intpath[5005],top;vector<int>ARC[MAXN];voidDfsintu) {     for(intI=0, Size=arc[u].size (); i<size;i++)    {        intId=Arc[u][i]; if(!Vis[id]) {Vis[id]=1; intv=es[id].getto (U);        DFS (v); }} path[top++]=u;}intMain () { while(SCANF ("%d%d", &n,&m)! =EOF) {memset (deg,0,sizeof(deg)); memset (Vis,0,sizeof(VIS));  for(intI=1; i<=n;i++) {arc[i].clear (); }         for(intI=1; i<=m;i++)        {            intu,v; scanf ("%d%d",&u,&v); ES[I].U=u; ES[I].V=v;            Arc[u].push_back (i);            Arc[v].push_back (i); Deg[u]++; DEG[V]++; }        /*WA??                for (int i=1;i<=n;i++) {if (deg[i]%2==1) {DFS (i);            Break }        }        */DFS (1);  for(intI=0; i<top-1; i++) {printf ("%d", Path[i]); } printf ("%d\n", path[top-1]); }    return 0;}

Forward-to-star implementations.

#include <cstdio>#include<cstring>using namespacestd;Const intmaxn=1005;structedge{intto,net; BOOLtag;} ES[MAXN*Ten];intn,m;intHead[maxn],tot;intpath[5005],top;intDEG[MAXN];voidAddedge (intUintv) {es[tot].to=v; Es[tot].tag=false; Es[tot].net=Head[u]; Head[u]=tot++;}voidDfsintu) {     for(inti=head[u];i!=-1; i=es[i].net) {        if(!Es[i].tag) {            intv=es[i].to;  for(intj=head[v];j!=-1; j=es[j].net) {                if(es[j].to==u&&!Es[j].tag) {Es[j].tag=true;  Break; }} Es[i].tag=true;        DFS (v); }} path[top++]=u;}intMain () {memset (head,-1,sizeof(head)); scanf ("%d%d",&n,&m);  for(intI=0; i<m;i++)    {        intu,v; scanf ("%d%d",&u,&v);        Addedge (U,V);        Addedge (V,u); Deg[u]++; DEG[V]++; }    /*wrong for (int i=1;i<=n;i++) {if (deg[i]%2==1) {DFS (i);        Break }    }    */DFS (1);//Accepted     for(intI=0; i<top-1; i++) {printf ("%d", Path[i]); } printf ("%d\n", path[top-1]); return 0;}

hihocoder#1181 (Euler path)