#include<bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef double db;
ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a ;} // greatest common divisor (PGCD)
ll lcm(ll a , ll b) {return (a * b) / gcd(a , b);} // least common multiple (PPCM)
#define ss second
#define ff first
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define vi vector<int>
#define vii vector<pair<int,int>>
#define vl vector<ll>
#define vll vector<pair<ll,ll>>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pdd pair<double,double>
#define vdd vector<pdd>
#define dte tuple<double , double , double>
using namespace std;
const int INF = 1000*1000*1000; // 1 e 9
const int MOD = 1e9 + 7;//998244353 ;
const double EPS = 0.000000001; // 1 e -9
const ll inf = (ll)1e18;
bool vis[22];
bool ok = true;
int n;
pll p[22];
void dfs(int pos , ll need){
//cout << pos << " " << need << "\n";
int i = pos;
if(vis[pos]) {
ok = false; return;
}
vis[pos] = true;
ll cur = p[i].ff - p[i].ss;
if(cur >= need) {
p[i].ff -= need; return;
}
ll nxt = (need - max((ll)0 , p[i].ff - p[i].ss) + max((ll)0 , p[i].ss - p[i].ff)) * 2;
int id = pos - 1; if(id == -1) id = n - 1;
dfs(id , nxt);
p[i].ff = p[i].ss;
}
int main(){
//ifstream fin ("testing.txt");
//ofstream fout ("output.txt");
ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
cin>>n;
if(n > 20) return 0;
for(int i = 0 ; i < n ; i++) cin>>p[i].ff>>p[i].ss;
for(int i = 0 ; i < n ; i++){
if(p[i].ff < p[i].ss){
memset(vis , 0 , sizeof vis);
ok = true;
dfs(i , 0);
if(!ok) return cout << "No\n",0;
}
}
for(int i = 0 ; i < n ; i++){
if(p[i].ff != p[i].ss) return cout << "No\n",0;
}
cout << "Yes\n";
return 0;
}
/*
Think of : BS / DFS / BFS / SSSP / SCC / MSP / MAX FLOW / TOPSORT / LCA / MATRIX / DP(bitmask) / 2 POINTERS / SEG TREE / MATH / UN FIND / MO / HLD
Read the statement CAREFULLY !!
Make a GREADY APPROACH !!!! (start from highest / lowest)
Make your own TESTS !!
Be careful from CORNER CASES !
*/
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
1 ms |
212 KB |
Output is correct |
3 |
Correct |
1 ms |
212 KB |
Output is correct |
4 |
Correct |
1 ms |
212 KB |
Output is correct |
5 |
Correct |
0 ms |
212 KB |
Output is correct |
6 |
Correct |
0 ms |
212 KB |
Output is correct |
7 |
Correct |
0 ms |
316 KB |
Output is correct |
8 |
Incorrect |
0 ms |
212 KB |
Output isn't correct |
9 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
1 ms |
212 KB |
Output is correct |
3 |
Correct |
1 ms |
212 KB |
Output is correct |
4 |
Correct |
1 ms |
212 KB |
Output is correct |
5 |
Correct |
0 ms |
212 KB |
Output is correct |
6 |
Correct |
0 ms |
212 KB |
Output is correct |
7 |
Correct |
0 ms |
316 KB |
Output is correct |
8 |
Incorrect |
0 ms |
212 KB |
Output isn't correct |
9 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
1 ms |
212 KB |
Output is correct |
3 |
Correct |
1 ms |
212 KB |
Output is correct |
4 |
Correct |
1 ms |
212 KB |
Output is correct |
5 |
Correct |
0 ms |
212 KB |
Output is correct |
6 |
Correct |
0 ms |
212 KB |
Output is correct |
7 |
Correct |
0 ms |
316 KB |
Output is correct |
8 |
Incorrect |
0 ms |
212 KB |
Output isn't correct |
9 |
Halted |
0 ms |
0 KB |
- |