给定n个元素的数组。任务是找到满足以下等式的六连体的数量，以使a，b，c，d，e和f属于给定数组：
a * b + c - e = f
d
例子：
Input : arr[] = { 1 }.
Output : 1
a = b = c = d = e = f = 1 satisfy
the equation.
Input : arr[] = { 2, 3 }
Output : 4
Input : arr[] = { 1, -1 }
Output : 24
首先，对方程重新排序，a * b + c =(f + e)* d。
现在，制作两个数组，一个用于方程式的LHS(左手边)，另一个用于方程式的RHS(右手边)。在LHS数组中搜索RHS数组的每个元素。每当在LHS中找到RHS的值时，请检查它在LHS中重复了多少次，并将该计数加到总数中。通过对LHS数组进行排序，可以使用二进制搜索来进行搜索。
以下是此方法的实现：
C++
// C++ program to count of 6 values from an array
// that satisfy an equation with 6 variables
#include
using namespace std;
// Returns count of 6 values from arr[]
// that satisfy an equation with 6 variables
int findSextuplets(int arr[], int n)
{
// Generating possible values of RHS of the equation
int index = 0;
int RHS[n*n*n + 1];
for (int i = 0; i < n; i++)
if (arr[i]) // Checking d should be non-zero.
for (int j = 0; j < n; j++)
for (int k = 0; k < n; k++)
RHS[index++] = arr[i] * (arr[j] + arr[k]);
// Sort RHS[] so that we can do binary search in it.
sort(RHS, RHS + n);
// Generating all possible values of LHS of the equation
// and finding the number of occurances of the value in RHS.
int result = 0;
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
for(int k = 0; k < n; k++)
{
int val = arr[i] * arr[j] + arr[k];
result += (upper_bound(RHS, RHS + index, val) -
lower_bound(RHS, RHS + index, val));
}
}
}
return result;
}
// Driven Program
int main()
{
int arr[] = {2, 3};
int n = sizeof(arr)/sizeof(arr[0]);
cout << findSextuplets(arr, n) << endl;
return 0;
} Java
// Java program to count of 6 values from an array
// that satisfy an equation with 6 variables
import java.util.Arrays;
class GFG{
static int upper_bound(int[] array, int length, int value) {
int low = 0;
int high = length;
while (low < high) {
final int mid = (low + high) / 2;
if (value >= array[mid]) {
low = mid + 1;
} else {
high = mid;
}
}
return low;
}
static int lower_bound(int[] array, int length, int value) {
int low = 0;
int high = length;
while (low < high) {
final int mid = (low + high) / 2;
if (value <= array[mid]) {
high = mid;
} else {
low = mid + 1;
}
}
return low;
}
static int findSextuplets(int[] arr, int n)
{
// Generating possible values of RHS of the equation
int index = 0;
int[] RHS = new int[n * n * n + 1];
for (int i = 0; i < n; i++)
{
if (arr[i] != 0) // Checking d should be non-zero.
{
for (int j = 0; j < n; j++)
{
for (int k = 0; k < n; k++)
{
RHS[index++] = arr[i] * (arr[j] + arr[k]);
}
}
}
}
// Sort RHS[] so that we can do binary search in it.
Arrays.sort(RHS);
// Generating all possible values of LHS of the equation
// and finding the number of occurances of the value in RHS.
int result = 0;
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
for (int k = 0; k < n; k++)
{
int val = arr[i] * arr[j] + arr[k];
result += (upper_bound(RHS, index, val)-lower_bound(RHS, index, val));
}
}
}
return result;
}
// Driven Program
public static void main(String[] args)
{
int[] arr = {2, 3};
int n = arr.length;
System.out.println(findSextuplets(arr, n));
}
}
// This code is contributed by mitsPython3
# Python3 program to count of 6 values
# from an array that satisfy an equation
# with 6 variables
def upper_bound(array, length, value):
low = 0;
high = length;
while (low < high):
mid = int((low + high) / 2);
if (value >= array[mid]):
low = mid + 1;
else:
high = mid;
return low;
def lower_bound(array, length, value):
low = 0;
high = length;
while (low < high):
mid = int((low + high) / 2);
if (value <= array[mid]):
high = mid;
else:
low = mid + 1;
return low;
def findSextuplets(arr, n):
# Generating possible values of
# RHS of the equation
index = 0;
RHS = [0] * (n * n * n + 1);
for i in range(n):
if (arr[i] != 0):
# Checking d should be non-zero.
for j in range(n):
for k in range(n):
RHS[index] = arr[i] * (arr[j] +
arr[k]);
index += 1;
# Sort RHS[] so that we can do
# binary search in it.
RHS.sort();
# Generating all possible values of
# LHS of the equation and finding the
# number of occurances of the value in RHS.
result = 0;
for i in range(n):
for j in range(n):
for k in range(n):
val = arr[i] * arr[j] + arr[k];
result += (upper_bound(RHS, index, val) -
lower_bound(RHS, index, val));
return result;
# Driver Code
arr = [2, 3];
n = len(arr);
print(findSextuplets(arr, n));
# This code is contributed by mitsC#
// C# program to count of 6 values from an array
// that satisfy an equation with 6 variables
using System;
using System.Collections;
class GFG{
static int upper_bound(int[] array, int length, int value) {
int low = 0;
int high = length;
while (low < high) {
int mid = (low + high) / 2;
if (value >= array[mid]) {
low = mid + 1;
} else {
high = mid;
}
}
return low;
}
static int lower_bound(int[] array, int length, int value) {
int low = 0;
int high = length;
while (low < high) {
int mid = (low + high) / 2;
if (value <= array[mid]) {
high = mid;
} else {
low = mid + 1;
}
}
return low;
}
static int findSextuplets(int[] arr, int n)
{
// Generating possible values of RHS of the equation
int index = 0;
int[] RHS = new int[n * n * n + 1];
for (int i = 0; i < n; i++)
{
if (arr[i] != 0) // Checking d should be non-zero.
{
for (int j = 0; j < n; j++)
{
for (int k = 0; k < n; k++)
{
RHS[index++] = arr[i] * (arr[j] + arr[k]);
}
}
}
}
// Sort RHS[] so that we can do binary search in it.
Array.Sort(RHS);
// Generating all possible values of LHS of the equation
// and finding the number of occurances of the value in RHS.
int result = 0;
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
for (int k = 0; k < n; k++)
{
int val = arr[i] * arr[j] + arr[k];
result += (upper_bound(RHS, index, val)-lower_bound(RHS, index, val));
}
}
}
return result;
}
// Driven Program
static void Main()
{
int[] arr = {2, 3};
int n = arr.Length;
Console.WriteLine(findSextuplets(arr, n));
}
}
// This code is contributed by mitsPHP
= $array[$mid])
$low = $mid + 1;
else
$high = $mid;
}
return $low;
}
function lower_bound($array, $length, $value)
{
$low = 0;
$high = $length;
while ($low < $high)
{
$mid = (int)(($low + $high) / 2);
if ($value <= $array[$mid])
$high = $mid;
else
$low = $mid + 1;
}
return $low;
}
// Returns count of 6 values from arr[]
// that satisfy an equation with 6 variables
function findSextuplets($arr, $n)
{
// Generating possible values of
// RHS of the equation
$index = 0;
$RHS = array_fill(0, $n * $n * $n + 1, 0);
for ($i = 0; $i < $n; $i++)
if ($arr[$i] != 0) // Checking d should be non-zero.
for ($j = 0; $j < $n; $j++)
for ($k = 0; $k < $n; $k++)
$RHS[$index++] = $arr[$i] *
($arr[$j] + $arr[$k]);
// Sort RHS[] so that we can do
// binary search in it.
sort($RHS);
// Generating all possible values of LHS
// of the equation and finding the number
// of occurances of the value in RHS.
$result = 0;
for ($i = 0; $i < $n; $i++)
for ($j = 0; $j < $n; $j++)
for ($k = 0; $k < $n; $k++)
{
$val = $arr[$i] * $arr[$j] + $arr[$k];
$result += (upper_bound($RHS, $index, $val) -
lower_bound($RHS, $index, $val));
}
return $result;
}
// Driver Code
$arr = array(2, 3);
$n = count($arr);
print(findSextuplets($arr, $n));
// This code is contributed by mits
?>输出：
4
时间复杂度： O(N 3 log N)