1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
| #include <bits/stdc++.h>
using namespace std;
#define Code ios_base::sync_with_stdio(false);
#define By cin.tie(NULL);
#define Sumfi cout.tie(NULL);
using ll= long long;
using lld= long double;
using ull= unsigned long long;
const lld pi= 3.141592653589793238;
const ll INF= 1e18;
const ll mod=1e9+7;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<pll> vpll;
typedef vector<string> vs;
typedef unordered_map<ll,ll> umll;
typedef map<ll,ll> mll;
#define ff first
#define ss second
#define pb push_back
#define ist insert
#define has count
#define mp make_pair
#define fl(i,n) for(int i=0;i<n;i++)
#define rl(i,m,n) for(int i=n;i>=m;i--)
#define py cout<<"YES\n";
#define pm cout<<"-1\n";
#define pn cout<<"NO\n";
#define vr(v) v.begin(),v.end()
#define rv(v) v.end(),v.begin()
#ifdef AbhinavAwasthi
#define debug(x) cerr << #x<<" "; cerr<<x<<" "; cerr << endl;
#else
#define debug(x);
#endif
template<typename T1, typename T2>
istream& operator>>(istream &istream, pair<T1, T2> &p) { return (istream >> p.first >> p.second); }
template<typename T>
istream& operator>>(istream &istream, vector<T> &v){for (auto &it : v)cin >> it;return istream;}
template<typename T1, typename T2>
ostream& operator<<(ostream &ostream, const pair<T1, T2> &p) { return (ostream << p.first << " " << p.second); }
template<typename T>
ostream& operator<<(ostream &ostream, const vector<T> &c) { for (auto &it : c) cout << it << " "; return ostream; }
template <typename T>
void print(T &&t) { cout << t << "\n"; }
void printarr(ll arr[], ll n){fl(i,n) cout << arr[i] << " ";cout << "\n";}
template<typename T>
void printvec(vector<T>v){ll n=v.size();fl(i,n)cout<<v[i]<<" ";cout<<"\n";}
template<typename T>
ll sumvec(vector<T>v){ll n=v.size();ll s=0;fl(i,n)s+=v[i];return s;}
ll gcd(ll a, ll b){if (b == 0)return a;return gcd(b, a % b);}
ll lcm(ll a, ll b){return (a/gcd(a,b)*b);}
ll moduloMultiplication(ll a,ll b,ll mod){ll res = 0;a %= mod;while (b){if (b & 1)res = (res + a) % mod;b >>= 1;}return res;}
ll powermod(ll x, ll y, ll p){ll res = 1;x = x % p;if (x == 0) return 0;while (y > 0){if (y & 1)res = (res*x) % p;y = y>>1;x = (x*x) % p;}return res;}
ll powerll(ll x, ll n){ll res=1;while(n){if (n & 1){res=res * x;}n>>=1;x*=x;}return res;}
bool sorta(const pair<int,int> &a,const pair<int,int> &b){return (a.second < b.second);}
bool sortd(const pair<int,int> &a,const pair<int,int> &b){return (a.second > b.second);}
string decToBinary(int n){string s="";int i = 0;while (n > 0) {s =to_string(n % 2)+s;n = n / 2;i++;}return s;}
ll binaryToDecimal(string n){string num = n;ll dec_value = 0;int base = 1;int len = num.length();for(int i = len - 1; i >= 0; i--){if (num[i] == '1')dec_value += base;base = base * 2;}return dec_value;}
bool isPrime(ll n){if(n<=1)return false;if(n<=3)return true;if(n%2==0||n%3==0)return false;for(int i=5;i*i<=n;i=i+6)if(n%i==0||n%(i+2)==0)return false;return true;}
bool isPowerOfTwo(int n){if(n==0)return false;return (ceil(log2(n)) == floor(log2(n)));}
bool isPerfectSquare(ll x){if (x >= 0) {ll sr = sqrt(x);return (sr * sr == x);}return false;}
ll graphParent(vll& v,ll n) {return v[n]==n?n:v[n]=graphParent(v,v[n]);}
void graphMerge(vll& v,ll a,ll b) {ll aa=graphParent(v,a),bb=graphParent(v,b);if(aa>bb){swap(aa,bb);}v[aa]=v[bb]=aa;}
#define MAX_N 2020
int n, m, c;
ll rep[MAX_N];
ll vis1[MAX_N], vis2[MAX_N];
vll adj[MAX_N];
vvll ans;
vll st;
ll dfs(ll u) {
st.pb(u);
ll res = vis1[u] = ++c, tp;
for(auto& v : adj[u]) {
if(!vis1[v]) res = min(res, dfs(v));
else if(!vis2[v]) res = min(res,vis1[v]);
}
if(res != vis1[u]) return res;
ans.pb(vll());
do {
tp = st.back(); st.pop_back();
rep[tp] = vis2[tp] = ans.size();
ans.back().pb(tp);
}while(tp != u);
return res;
}
ll NOT(ll u) {
return u > n ? u - n : u + n;
}
string sumfi()
{
memset(vis1,false, sizeof(vis1));
memset(vis2, false, sizeof(vis2));
memset(rep, 0, sizeof(rep));
st.clear();
ans.clear();
c = 0;
for(ll i = 1; i <= n * 2; i++) {
if(!vis1[i])
dfs(i);
}
for(ll i = 1; i <= n; i++)
if(rep[i] == rep[n + i])
return "no";
return "yes";
}
int main()
{
Code By Sumfi
while (scanf("%d%d",&n,&m) != EOF) {
for(ll i = 0; i < MAX_N; i++)
adj[i].clear();
while(m--) {
int u, v;
scanf("%d%d",&u,&v);
u = u < 0 ? -u + n : u;
v = v < 0 ? -v + n : v;
if (u == 1 || v == n+1) v = u;
if (v == 1 || u == n+1) u = v;
adj[NOT(u)].pb(v);
adj[NOT(v)].pb(u);
}
cout<<sumfi()<<'\n';
}
return 0;
}
|
