Alien Invasion CodeChef Solution

Problem -Alien Invasion CodeChef Solution

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Alien Invasion CodeChef Solution in C++17

#include <bits/stdc++.h>
using namespace std;
#define ll long long

double m, mid, l, r, k, ans, temp, cd;
int n, t, d;
int a[200001];
bool check(double c) {
    cd = 0;
    for (int i = 1; i <= n; i++) {
       if (cd > a[i] + d) {
           return false;
        } else if (cd < a[i]) {
            cd = a[i] + c;
        } else {
            cd = cd + c;
        }
    }
    return true;
}

int main() {
    cin >> t;
    for (int h = 1; h <= t; h++) {
        cin >> n >> d;
        for (int i = 1; i <= n; i++) {
            cin >> a[i];
        }
        sort(a + 1, a + n + 1);
        r = 2e9;
        l = 0;
        temp = 0;
        for (int i = 1; i <= 101; i++) {
            mid = (l+r)/2;
            if (check(mid) == true) {
                temp = mid;
                l = mid;
            } else {
                r = mid;
            }
        }
        cout << fixed << setprecision(10) << temp << endl;
    }
}

Alien Invasion CodeChef Solution in C++14

#ifndef ONLINE_JUDGE
#include "debug.h"
#else
#include <bits/stdc++.h>
using namespace std;
#endif
#define int long long int

int n,d;
double v[100001];

bool f(double t)
{
    double curr=v[0]+t;
    int i;
    for(i=1;i<n;i++)
    {
        if(v[i]+d>=curr)
        {
            curr=max(curr,v[i]);
            curr+=t;
        }
        else
        break;
    }
    return (i==n);
}

void solve()
{
    cin>>n>>d;
    for(int i=0;i<n;i++)
    cin>>v[i];
    sort(v,v+n);
    double l=0,r=1e10;
    while(r-l>1e-6)
    {
        double mid=(l+r)/2;
        if(f(mid))
        l=mid;
        else
        r=mid;
    }
    cout<<fixed<<setprecision(6)<<l<<'\n';
}
int32_t main() 
{
#ifndef ONLINE_JUDGE
    freopen("input.txt","r",stdin);
    freopen("Error.txt","w",stderr);
    freopen("output.txt","w",stdout);
#endif
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t=1;
    cin>>t;
    while(t--)
    solve();
	return 0;
}

Alien Invasion CodeChef Solution in C

//set many funcs template
//Ver.20190820
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<stdbool.h>
#include<time.h>
#include<assert.h>
#define inf 1072114514
#define llinf 4154118101919364364
#define mod 1000000007
#define pi 3.1415926535897932384

int max(int a,int b){if(a>b){return a;}return b;}
int min(int a,int b){if(a<b){return a;}return b;}
int zt(int a,int b){return max(a,b)-min(a,b);}
int round(int a,int b){if((a%b)*2 >= b){return (a/b)+1;}return a/b;}
int ceil(int a,int b){if(a%b==0){return a/b;}return (a/b)+1;}
int gcd(int a,int b){int c;while(b!=0){c=a%b;a=b;b=c;}return a;}
int lcm(int a,int b){int c=gcd(a,b);a/=c;return a*b;}
int nCr(int a,int b){int i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;}
int nHr(int a,int b){return nCr(a+b-1,b);}
int fact(int a){int i,r=1;for(i=1;i<=a;i++){r*=i;}return r;}
int pow(int a,int b){int i,r=1;for(i=1;i<=b;i++){r*=a;}return r;}
int dsum(int x){int r=0;while(x){r+=(x%10);x/=10;}return r;}
int dsumb(int x,int b){int r=0;while(x){r+=(x%b);x/=b;}return r;}
int sankaku(int x){return ((1+x)*x)/2;}
void swap(int *a,int *b){int c;c=(*a);(*a)=(*b);(*b)=c;}
long long llmax(long long a,long long b){if(a>b){return a;}return b;}
long long llmin(long long a,long long b){if(a<b){return a;}return b;}
long long llzt(long long a,long long b){return llmax(a,b)-llmin(a,b);}
long long llround(long long a,long long b){if((a%b)*2 >= b){return (a/b)+1;}return a/b;}
long long llceil(long long a,long long b){if(a%b==0){return a/b;}return (a/b)+1;}
long long llgcd(long long a,long long b){long long c;while(b!=0){c=a%b;a=b;b=c;}return a;}
long long lllcm(long long a,long long b){long long c=llgcd(a,b);a/=c;return a*b;}
long long llnCr(long long a,long long b){long long i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;}
long long llnHr(long long a,long long b){return llnCr(a+b-1,b);}
long long llfact(long long a){long long i,r=1;for(i=1;i<=a;i++){r*=i;}return r;}
long long llpow(long long a,long long b){long long i,r=1;for(i=1;i<=b;i++){r*=a;}return r;}
long long lldsum(long long x){long long r=0;while(x){r+=(x%10);x/=10;}return r;}
long long lldsumb(long long x,long long b){long long r=0;while(x){r+=(x%b);x/=b;}return r;}
long long llsankaku(long long x){return ((1+x)*x)/2;}
void llswap(long long *a,long long *b){long long c;c=(*a);(*a)=(*b);(*b)=c;}
double dbmax(double a,double b){if(a>b){return a;}return b;}
double dbmin(double a,double b){if(a<b){return a;}return b;}
double dbzt(double a,double b){return dbmax(a,b)-dbmin(a,b);}
void dbswap(double *a,double *b){double c;c=(*a);(*a)=(*b);(*b)=c;}
void chswap(char *a,char *b){char c;c=(*a);(*a)=(*b);(*b)=c;}
int sortfncsj(const void *a,const void *b){if(*(int *)a>*(int *)b){return 1;}if(*(int *)a==*(int *)b){return 0;}return -1;}
int sortfnckj(const void *a,const void *b){if(*(int *)a<*(int *)b){return 1;}if(*(int *)a==*(int *)b){return 0;}return -1;}
int llsortfncsj(const void *a,const void *b){if(*(long long *)a>*(long long *)b){return 1;}if(*(long long *)a==*(long long *)b){return 0;}return -1;}
int llsortfnckj(const void *a,const void *b){if(*(long long *)a<*(long long *)b){return 1;}if(*(long long *)a==*(long long *)b){return 0;}return -1;}
int dbsortfncsj(const void *a,const void *b){if(*(double *)a>*(double *)b){return 1;}if(*(double *)a==*(double *)b){return 0;}return -1;}
int dbsortfnckj(const void *a,const void *b){if(*(double *)a<*(double *)b){return 1;}if(*(double *)a==*(double *)b){return 0;}return -1;}
int strsortfncsj(const void *a,const void *b){return strcmp((char *)a,(char *)b);}
int strsortfnckj(const void *a,const void *b){return strcmp((char *)b,(char *)a);}
int chsortfncsj(const void *a,const void *b){if(*(char *)a>*(char *)b){return 1;}if(*(char *)a==*(char *)b){return 0;}return -1;}
int chsortfnckj(const void *a,const void *b){if(*(char *)a<*(char *)b){return 1;}if(*(char *)a==*(char *)b){return 0;}return -1;}

void shuffledget(int x[],int n){
    int i,b[524288],p,c;
    for(i=0;i<n;i++){
        b[i]=i;
    }
    for(i=n;i>=1;i--){
        p=rand()%i;
        c=b[i-1];b[i-1]=b[p];b[p]=c;
    }
    for(i=0;i<n;i++){
        scanf("%d",&x[b[i]]);
    }
}

int dx4[4]={1,-1,0,0};
int dy4[4]={0,0,1,-1};
int dx8[8]={-1,-1,-1,0,0,1,1,1};
int dy8[8]={-1,0,1,-1,1,-1,0,1};

int search(int x,int a[],int n){
    int st=0,fi=n-1,te;
    while(st<=fi){
        te=(st+fi)/2;
        if(a[te]<x){st=te+1;}else{fi=te-1;}
    }
    return st;
}

void prarr(int arr[],int n){
  int i;
  for(i=0;i<n;i++){
    if(i){printf(" ");}
    printf("%d",arr[i]);
  }
  printf("\n");
  return;
}

void getperm(int a[],int n){
  int i,p;
  for(i=0;i<n;i++){
    a[i]=i;
  }
  for(i=n-1;i>=1;i--){
    p=rand()%(i+1);
    swap(&a[p],&a[i]);
  }
}

typedef struct{
int val;
int node;
}sd;

int sdsortfnc(const void *a,const void *b){
if(((sd*)a)->val < ((sd*)b)->val){return -1;}
if(((sd*)a)->val > ((sd*)b)->val){return 1;}
return 0;
}

void coordinate_comp(int a[],int n){
  int i,c=0;
  sd dat[524288];
  for(i=0;i<n;i++){
    dat[i].val=a[i];
    dat[i].node=i;
  }
  qsort(dat,n,sizeof(dat[0]),sdsortfnc);
  a[dat[0].node]=c;
  for(i=1;i<n;i++){
    if(dat[i-1].val!=dat[i].val){c++;}
    a[dat[i].node]=c;
  }
}

int main(void){
  int n,i,j,t;
  double d,a[524288],st,fi,te,cl;
  scanf("%d",&t);
  while(t>0){
    t--;
    scanf("%d%lf",&n,&d);
    for(i=0;i<n;i++){scanf("%lf",&a[i]);}
    qsort(a,n,sizeof(double),dbsortfncsj);
    st=0;fi=3.0e9;
    for(i=0;i<200;i++){
      te=(st+fi)/2.0;
      cl=-3.0e9;
      for(j=0;j<n;j++){
        cl=dbmax(a[j],cl+te);
        if(cl>a[j]+d){fi=te;break;}
        if(j==n-1){st=te;}
      }
    }
    printf("%.12lf\n",fi);
  }
  return 0;
}

Alien Invasion CodeChef Solution in JAVA

import java.util.*;

class Main {
    
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int t = input.nextInt();
        while(t-- > 0) {
            int n = input.nextInt(), d = input.nextInt();
            int[] arr = new int[n];
            for (int i = 0; i < n; i++) {
                arr[i] = input.nextInt();
            }
            Arrays.sort(arr);
            double low = 0, high = 2e9;
            while (low + 1e-6 <= high) {
                double mid = 0.5 * (low + high);
                if (isvalid(arr, d, mid, n)) {
                    low = mid;
                } else {
                    high = mid;
                }
            }
            System.out.println(low);
        }
        input.close();
    }
    private static boolean isvalid(int[] arr, int d, double mid, int n) {
        double kill = 0.0;
        for (int i = 0; i < n; i++) {
            if (kill <= arr[i] + d) {
                kill = Math.max(arr[i] + mid, kill + mid);
            } else {
                return false;
            }
        }
        return true;
    }
}

Alien Invasion CodeChef Solution in PYPY 3

from sys import stdin
input = stdin.readline


def check(x):

    cooldown = 0
    for i in range(n):
        if(cooldown > (c[i] + d)):return False
        cooldown = max(cooldown , c[i]) + x
        
    return True


def answer():

    l , r = 0 , 10**10
    
    for i in range(101):

        mid = (l + r)/2

        if(check(mid)):
            l = mid
            ans = mid
        else:
            r = mid

    return ans
    
        
for T in range(int(input())):

    n , d = map(int,input().split())

    c = sorted(list(map(int,input().split())))
   
  
    print(answer())

Alien Invasion CodeChef Solution in GO

package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"sort"
)

func main() {
	reader := bufio.NewReader(os.Stdin)

	tc := readNum(reader)

	for tc > 0 {
		tc--
		n, D := readTwoNums(reader)
		C := readNNums(reader, n)
		res := solve(n, D, C)
		fmt.Printf("%.7f\n", res)
	}
}

func readInt(bytes []byte, from int, val *int) int {
	i := from
	sign := 1
	if bytes[i] == '-' {
		sign = -1
		i++
	}
	tmp := 0
	for i < len(bytes) && bytes[i] >= '0' && bytes[i] <= '9' {
		tmp = tmp*10 + int(bytes[i]-'0')
		i++
	}
	*val = tmp * sign
	return i
}

func readNum(reader *bufio.Reader) (a int) {
	bs, _ := reader.ReadBytes('\n')
	readInt(bs, 0, &a)
	return
}

func readTwoNums(reader *bufio.Reader) (a int, b int) {
	res := readNNums(reader, 2)
	a, b = res[0], res[1]
	return
}

func readThreeNums(reader *bufio.Reader) (a int, b int, c int) {
	res := readNNums(reader, 3)
	a, b, c = res[0], res[1], res[2]
	return
}

func readNNums(reader *bufio.Reader, n int) []int {
	res := make([]int, n)
	x := 0
	bs, _ := reader.ReadBytes('\n')
	for i := 0; i < n; i++ {
		for x < len(bs) && (bs[x] < '0' || bs[x] > '9') && bs[x] != '-' {
			x++
		}
		x = readInt(bs, x, &res[i])
	}
	return res
}

func readUint64(bytes []byte, from int, val *uint64) int {
	i := from

	var tmp uint64
	for i < len(bytes) && bytes[i] >= '0' && bytes[i] <= '9' {
		tmp = tmp*10 + uint64(bytes[i]-'0')
		i++
	}
	*val = tmp

	return i
}

func solve(n int, D int, C []int) float64 {
	sort.Ints(C)

	check := func(cooldown float64) bool {
		var canFireAt float64

		for i := 0; i < n; i++ {
			a := float64(C[i])
			b := float64(C[i] + D)

			if canFireAt > b {
				return false
			}
			canFireAt = math.Max(a, canFireAt) + cooldown
		}
		return true
	}

	var left, right float64 = 0, float64(int64(1) << 33)

	for i := 0; i < 60; i++ {
		mid := (left + right) / 2
		if check(mid) {
			left = mid
		} else {
			right = mid
		}
	}
	return (left + right) / 2
}
Alien Invasion CodeChef Solution Review:

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