Submission #1445295

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Source Code Expand

#include <bits/stdc++.h>
  
using namespace std;
  
#define rep(i,n) REP(i,0,n)
#define REP(i,s,e) for(int i=(s); i<(int)(e); i++)
#define pb push_back
#define all(r) r.begin(),r.end()
#define rall(r) r.rbegin(),r.rend()
#define fi first
#define se second
  
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
 
const int INF = 1e9;
const ll MOD = 1e9 + 7;
double EPS = 1e-8;

int main(){
	ll n, k;
	cin >> n >> k;
	vl a(n);
	rep(i, n) {
		cin >> a[i];
		if(a[i] == k) {
			cout << "POSSIBLE" << endl;
			return 0;
		}
	}
	sort(all(a));
	if(a.back() < k || n == 1) {
		cout << "IMPOSSIBLE" << endl;
		return 0;
	}
	bool f = false;
	if(n == 2) {
		if(a[0] != a[1]) cout << "POSSIBLE" << endl;
		else cout << "IMPOSSIBLE" << endl;
		return 0;
	}
	ll dif = a[1] - a[0];
	REP(i, 1, n) {
		if(a[i] - a[i-1] != dif) f = true;
	}
	cout << (f ? "POSSIBLE" : "IMPOSSIBLE") << endl;
}

Submission Info

Judge Result