Submission #8538550

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define INF 1LL<<62
#define inf 1000000007
typedef struct{
	double x;
	double y;
} vector2D;

vector2D nearest( vector2D A, vector2D B, vector2D P ){
	vector2D a, b;
	double r;
	
	a.x = B.x - A.x;
	a.y = B.y - A.y;
	b.x = P.x - A.x;
	b.y = P.y - A.y;
	
	r = (a.x*b.x + a.y*b.y) / (a.x*a.x + a.y*a.y);
	
	if( r<= 0 ){
		return A;
	}else if( r>=1 ){
		return B;
	}else{
		vector2D result;
		result.x = A.x + r*a.x;
		result.y = A.y + r*a.y;
		return result;
	}
}
double c[11],d[11];
int main() {
	double a,b;
	ll n;
	cin>>a>>b>>n;
	double ans=inf;
	for(ll i=0;i<n;i++){
		cin>>c[i]>>d[i];
	}
	c[n]=c[0],d[n]=d[0];
	for(ll i=1;i<=n;i++){
		vector2D A={a,b};
		vector2D B={c[i-1],d[i-1]};
		vector2D C={c[i],d[i]};
		vector2D D=nearest(B,C,A);
		double dx=sqrt((A.x-D.x)*(A.x-D.x)+(A.y-D.y)*(A.y-D.y));
		ans=min(ans,dx);
	}
	printf("%.10f\n",ans);
	// your code goes here
	return 0;
}

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