Here you will find solutions of many problems on spoj. If you want solution of some problem which is not listed in blog or have doubt regarding any spoj problem (which i have solved) or any programming concept (data structure) you can mail me @ raj.nishant360@gmail.com
And my humble request to you all that don't copy the code only try to understand the logic and algorithm behind the code. I have started this because if you tried as hard as you can and still can't find any solution to the problem then you can refer to this.
You can read my answer how to start competitive programming CLICK HERE

Thursday, October 22, 2015

BSHEEP-Build the Fence

Build the Fence 

Given below code is for bsheep spoj or build the fence spoj.

Hint:- Simple implementation of any O(N log N) algorithm for  Convex Hull. 





/*
===================================================
Name :- Nishant Raj
Email :- raj.nishant360@gmail.com
College :- Indian School of Mines
Branch :- Computer Science and Engineering
Time :- 22 October 2015 (Thursday) 09:33
===================================================*/
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair < int , int >
#define pb push_back
#define mp make_pair
#define mod 1000000009
class point{
public:
    int x , y , pos;
    point(){};
    point(int a , int b , int c){x = a , y = b , pos = c;}
    double distance(point &a){
        int dx = a.x - x;
        int dy = a.y - y;
        return sqrt(dx*dx + dy*dy);
    }
    bool operator != (point &a){
        if(a.x != x || a.y != y)
            return true;
        return false;
    }
};
bool cmp(const point &a , const point &b){
    return a.y == b.y ? (a.x == b.x ? a.pos < b.pos : a.x < b.x ): a.y < b.y;
}
int orientation( point P , point Q , point R ){
    return  ( Q.x - P.x ) * ( R.y - P.y ) - ( R.x - P.x ) * ( Q.y - P.y );
}
void convex_hull(vector<point> &p , vector<point> &upper , vector<point> &lower){
    sort(p.begin() , p.end() , cmp);
    int k = 1;
    for(int i = 1 ; i < p.size() ; i++)
        if(p[i-1] != p[i])
            p[k++] = p[i];
    p.resize(k);
    int sz = 2*k;
    upper.resize(sz);
    lower.resize(sz);
    int j = 0 ;
    k = 0;
    for(int i = 0 ; i < p.size() ; i++){
        while(j >= 2 && orientation(lower[j-2] , lower[j-1] , p[i]) <= 0)
            j--;
        while(k >=2 && orientation(upper[k-2] , upper[k-1] , p[i]) >= 0)
            k--;
        lower[j++] = p[i];
        upper[k++] = p[i];
    }
    lower.resize(j);
    upper.resize(k);
}
int main(){
    
    int t;
    scanf("%d",&t);
    while(t--){
        int n;
        scanf("%d",&n);
        vector<point> v;
        int x , y;
        for(int i = 0 ; i < n ; i++){
            scanf("%d%d",&x , &y);
            v.pb(point(x , y , i+1));
        }
        vector<point> lower , upper;
        convex_hull(v , upper , lower);
        for(int i = upper.size() - 2 ; i > 0 ; i--)
            lower.pb(upper[i]);
        double dist = 0.0;
        for(int i = 1 ; i < lower.size() ; i++)
            dist += lower[i-1].distance(lower[i]);
        dist += lower[lower.size() -1].distance(lower[0]);
        printf("%.2lf\n", dist);
        for(int i = 0 ; i < lower.size() ; i++)
            printf("%d ", lower[i].pos);
        printf("\n");
    }
    
    return 0;
}