Function

input/code.cpp: In function 'bool convex_hull(std::vector<Point>)':
input/code.cpp:63:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<H.size();i++) ma[H[i]]=i;
              ~^~~~~~~~~
input/code.cpp:64:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i+1<P.size();i++)
              ~~~^~~~~~~~~

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;
 
#define fi first
#define se second
#define mp make_pair
#define pb push_back
 
typedef long long ll;
typedef pair<ll,ll> ii;
typedef vector<int> vi;
typedef unsigned long long ull;
typedef long double ld; 
typedef tree<ii, null_type, less<ii>, rb_tree_tag, tree_order_statistics_node_update> pbds;

typedef ll coord_t;         // coordinate type
typedef ll coord2_t;  // must be big enough to hold 2*max(|coordinate|)^2

struct Point {
	coord_t x, y;

	bool operator <(const Point &p) const {
		return x < p.x || (x == p.x && y < p.y);
	}
};

// 2D cross product of OA and OB vectors, i.e. z-component of their 3D cross product.
// Returns a positive value, if OAB makes a counter-clockwise turn,
// negative for clockwise turn, and zero if the points are collinear.
coord2_t cross(const Point &O, const Point &A, const Point &B)
{
	return (A.x - O.x) * (B.y - O.y) - (A.y - O.y) * (B.x - O.x);
}

map<Point,int> ma;
bool convex_hull(vector<Point> P)
{
	size_t n = P.size(), k = 0;
	if (n <= 3) return n;
	vector<Point> H(2*n);
	vector<Point> orip=P;
	// Sort points lexicographically
	sort(P.begin(), P.end());

	// Build lower hull
	for (size_t i = 0; i < n; ++i) {
		while (k >= 2 && cross(H[k-2], H[k-1], P[i]) <= 0) k--;
		H[k++] = P[i];
	}

	// Build upper hull
	for (size_t i = n-1, t = k+1; i > 0; --i) {
		while (k >= t && cross(H[k-2], H[k-1], P[i-1]) <= 0) k--;
		H[k++] = P[i-1];
	}

	H.resize(k-1);
	if(H.size()<P.size()) return false;
	for(int i=0;i<H.size();i++) ma[H[i]]=i;
	for(int i=0;i+1<P.size();i++)
	{
		int l = ma[orip[i]]; int r = ma[orip[i+1]];
		//cerr<<l<<' '<<r<<'\n';
		if(abs(l-r)!=1&&(min(l,r)!=0||max(l,r)!=int(P.size())-1)) return false;
	}
	return true;
}

void solve()
{
	int n; cin>>n;
	vector<Point> vec; ma.clear();
	for(int i=0;i<n;i++)
	{
		int x,y; cin>>x>>y;
		Point p; p.x=x; p.y=y;
		vec.pb(p); 
	}
	int res = convex_hull(vec);
	if(res) cout<<"YES\n";
	else cout<<"NO\n";
}

int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0);
	int t; cin>>t;
	while(t--) solve();
}

Test 1

Group: 1

Verdict: WRONG ANSWER

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: WRONG ANSWER

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 1

Verdict: WRONG ANSWER

Test 7

Group: 1

Verdict: WRONG ANSWER

Test 8

Group: 1

Verdict: ACCEPTED

Test 9

Group: 1

Verdict: WRONG ANSWER

Test 10

Group: 2

Verdict: WRONG ANSWER

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: WRONG ANSWER

Test 14

Group: 2

Verdict: ACCEPTED

Test 15

Group: 2

Verdict: WRONG ANSWER

Test 16

Group: 2

Verdict: WRONG ANSWER

Test 17

Group: 2

Verdict: WRONG ANSWER

Test 18

Group: 2

Verdict: ACCEPTED

Test 19

Group: 2

Verdict: ACCEPTED

Test 20

Group: 2

Verdict: WRONG ANSWER

Test 21

Group: 2

Verdict: WRONG ANSWER

Test 22

Group: 2

Verdict: ACCEPTED

Test 23

Group: 2

Verdict: WRONG ANSWER

Test 24

Group: 2

Verdict: WRONG ANSWER

Test 25

Group: 2

Verdict: ACCEPTED

Test 26

Group: 2

Verdict: WRONG ANSWER

Test 27

Group: 2

Verdict: WRONG ANSWER

Test 28

Group: 2

Verdict: ACCEPTED

Test 29

Group: 2

Verdict: WRONG ANSWER

Test 30

Group: 2

Verdict: ACCEPTED

Test 31

Group: 2

Verdict: ACCEPTED

Test 32

Group: 2

Verdict: WRONG ANSWER

Test 33

Group: 2

Verdict: WRONG ANSWER

Test 34

Group: 2

Verdict: ACCEPTED

Test 35

Group: 2

Verdict: ACCEPTED