#include<stdio.h>
#include<algorithm>
#include<vector>
#include<stdlib.h>
#define M 100010
using namespace std;
vector<int>con[M];
int arr3[M],dp[M][21],arr2[M],dap2,sw[M],dap,n,m,x,y,ch[M],anc[M],arr[M],w,top,lev[M],check[M],check2[M];
struct data{
int x,y,z;
bool operator<(const data&r)const{
return z<r.z;
}
}a[400010];
void dfs(int prev,int x,int p)
{
int i;
ch[x]=1; arr[++w]=x; lev[x]=p;
for(i=0;i<con[x].size();i++){
if(con[x][i]==prev && sw[x]==0){sw[x]=1; continue;}
if(ch[con[x][i]]){
if(lev[x]>=lev[con[x][i]]){top++; a[top].x=x; a[top].y=con[x][i];}
continue;
}
anc[con[x][i]]=x;
dfs(x,con[x][i],p+1);
}
}
int LCA(int x,int y)
{
int i;
if(lev[x]<lev[y]) swap(x,y);
for(i=0;i<=20;i++){
if((lev[x]-lev[y])&(1<<i)){
x=dp[x][i];
}
}
if(x==y){return x; return 0;}
for(i=20;i>=0;i--){
if(dp[x][i]!=0 && dp[x][i]!=dp[y][i]){x=dp[x][i]; y=dp[y][i];}
}
return dp[x][0];
}
void pro()
{
int i,j,s,p,sw=0,r,r2,cnt=0,cnt1=0,cnt2=0,gap=0,t=0,w2=0;
for(j=1;j<=20;j++){
for(i=1;i<=w;i++){
dp[arr[i]][j]=dp[dp[arr[i]][j-1]][j-1];
}
}
for(i=1;i<=top;i++) a[i].z=lev[a[i].y];
sort(a+1,a+top+1);
for(i=1;i<=top;i++){
s=lev[a[i].x]-lev[a[i].y];
if(s%2==1){
p=a[i].x; cnt1++;
while(check[p]==0){
if(p==a[i].y) break;
check[p]=1; cnt2++;
p=anc[p];
}
}
else if(!sw){
sw=1;
p=a[i].x; r=p; r2=a[i].y; t=s;
while(1){
if(p==a[i].y) break;
check2[p]=++w2; arr3[w2]=p;
p=anc[p];
}
}
}
if(sw==0){dap2+=w-1-cnt2; return;}
sw=0;
for(i=1;i<=top;i++){
s=lev[a[i].x]-lev[a[i].y];
if(s%2==0){
sw++; if(sw==1) continue;
p=LCA(r,t);
if(check2[p]==0 || lev[p]<lev[a[i].y]){printf("0"); exit(0);}
arr2[check2[p]]++; arr2[check2[a[i].y]+1]--;
}
}
p=0; cnt=0;
for(i=1;i<=w2;i++){
p+=arr2[i]; arr2[i]=0;
if(check[arr3[i]]==0 && p==sw-1) cnt++;
}
if(cnt==0 && top-cnt1>=2){printf("0"); exit(0);}
if(dap && cnt){printf("0"); exit(0);}
if(dap && (top-cnt1)){printf("0"); exit(0);}
dap+=cnt;
if(top-cnt1==1) dap++;
}
int main()
{
int i;
scanf("%d %d",&n,&m);
for(i=1;i<=m;i++){scanf("%d %d",&x,&y); con[x].push_back(y); con[y].push_back(x);}
for(i=1;i<=n;i++){
if(ch[i]==0){
dfs(0,i,1);
pro(); top=0; w=0;
}
}
if(dap==0) printf("%d",dap2);
else printf("%d",dap);
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
4 ms |
19960 KB |
Output is correct |
2 |
Correct |
0 ms |
19960 KB |
Output is correct |
3 |
Correct |
0 ms |
19960 KB |
Output is correct |
4 |
Correct |
0 ms |
19960 KB |
Output is correct |
5 |
Correct |
4 ms |
19960 KB |
Output is correct |
6 |
Correct |
0 ms |
19960 KB |
Output is correct |
7 |
Correct |
0 ms |
19960 KB |
Output is correct |
8 |
Correct |
0 ms |
19960 KB |
Output is correct |
9 |
Correct |
4 ms |
19960 KB |
Output is correct |
10 |
Correct |
0 ms |
19960 KB |
Output is correct |
11 |
Correct |
0 ms |
19960 KB |
Output is correct |
12 |
Correct |
4 ms |
19960 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
84 ms |
23512 KB |
Output is correct |
2 |
Correct |
140 ms |
26480 KB |
Output is correct |
3 |
Correct |
104 ms |
23512 KB |
Output is correct |
4 |
Correct |
140 ms |
27776 KB |
Output is correct |
5 |
Correct |
12 ms |
20304 KB |
Output is correct |
6 |
Correct |
128 ms |
25024 KB |
Output is correct |
7 |
Correct |
156 ms |
29120 KB |
Output is correct |
8 |
Correct |
136 ms |
29120 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
48 ms |
23512 KB |
Output is correct |
2 |
Correct |
52 ms |
29124 KB |
Output is correct |
3 |
Correct |
44 ms |
29120 KB |
Output is correct |
4 |
Correct |
0 ms |
19960 KB |
Output is correct |
5 |
Incorrect |
96 ms |
25316 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
96 ms |
24536 KB |
Output is correct |
2 |
Correct |
132 ms |
29116 KB |
Output is correct |
3 |
Correct |
12 ms |
19960 KB |
Output is correct |
4 |
Correct |
128 ms |
26464 KB |
Output is correct |
5 |
Correct |
144 ms |
27488 KB |
Output is correct |
6 |
Incorrect |
132 ms |
26176 KB |
Output isn't correct |
7 |
Halted |
0 ms |
0 KB |
- |