给定一个数组arr [] [],其中包含N个形式为[L,R]的查询,任务是找到每个查询范围内两个斐波那契数之间的最大差。如果范围内没有斐波那契数字,或者只有一个斐波那契数字,则打印0。
注意:所有范围都低于100005。
例子:
Input: N = 2, arr[][] = {{2, 2}, {2, 5}}
Output: 0 3
Explanation:
In the first query, there is only one Fibonacci number. So, the answer is 0.
In the second query, 2 is the minimum and 5 is the maximum Fibonacci number.
Therefore, the maximum difference = 3.
Input: N = 2, arr[][] = {{2, 21}, {30, 150}}
Output: 19 110
Explanation:
In the first query, 2 is the minimum and 5 is the maximum Fibonacci number.
Therefore, the maximum difference = 19.
In the second query, 34 is the minimum and 144 is the maximum Fibonacci number.
Therefore, the maximum difference = 110.
方法:想法是使用哈希和前缀和数组的概念来预先计算斐波纳契数并将其存储在两个数组prefix []和suffix []中。
完成上述预计算后,我们可以在固定时间内检查数字是否为斐波那契。因此,为了执行上述操作,使用了以下方法:
- 找到最大差异:为了找到最大差异,使用了为每个索引存储小于“ i”的最大斐波那契数的前缀数组和为每个索引存储大于“ i”的最小斐波那契数的后缀数组。对于每个查询{L,R},都返回前缀[R] –后缀[L] 。
- 找到最小差异: {L,R}范围内的前两个数字之间的差异是最小可能差异。
下面是上述方法的实现:
C++
// C++ program to find the maximum differences
// between two Fibonacci numbers in given ranges
#include
using namespace std;
#define MAX 100005
bool isFib[MAX];
int prefix[MAX], suffix[MAX];
// Function to precompute the Fibonacci,
// Prefix array and Suffix array
void precompute()
{
// Initializing it with False
memset(isFib, false, sizeof(isFib));
// Variable to store the Fibonacci
// numbers
// Marking the first two Fibonacci numbers
// as True in the array
int prev = 0, curr = 1;
isFib[prev] = isFib[curr] = true;
// Loop to iterate until the maximum number
while (curr < MAX) {
int temp = curr + prev;
isFib[temp] = true;
prev = curr;
curr = temp;
}
prefix[1] = 1;
suffix[MAX - 1] = 1e9 + 7;
// Precomputing Prefix array
for (int i = 2; i < MAX; i++) {
// If the number is a Fibonacci number,
// then adding it to the prefix array
if (isFib[i])
prefix[i] = i;
else
prefix[i] = prefix[i - 1];
}
// Precompute Suffix array
for (int i = MAX - 1; i > 1; i--) {
if (isFib[i])
suffix[i] = i;
else
suffix[i] = suffix[i + 1];
}
}
// Function to solve each query
int query(int L, int R)
{
if (prefix[R] < L || suffix[L] > R)
return 0;
else
return prefix[R] - suffix[L];
}
// Function to return the minimum difference
// between any two fibonacci numbers
// from the given range [L, R]
int minDifference(int L, int R)
{
// Find the first Fibonacci numbers
// from the range
int fst = 0;
for (int i = L; i <= R; i++) {
if (isFib[i]) {
fst = i;
break;
}
}
// Find the second Fibonacci numbers
// from the range
int snd = 0;
for (int i = fst + 1; i <= R; i++) {
if (isFib[i]) {
snd = i;
break;
}
}
// If the number of fibonacci numbers in
// the given range is < 2
if (snd == 0)
return -1;
// To store the minimum difference between
// two consecutive fibonacci numbers from the range
int diff = snd - fst;
// Range left to check for fibonacci numbers
int left = snd + 1;
int right = R;
// For every integer in the range
for (int i = left; i <= right; i++) {
// If the current integer is fibonacci
if (isFib[i]) {
// If the difference between i
// and snd is minimum so far
if (i - snd <= diff) {
fst = snd;
snd = i;
diff = snd - fst;
}
}
}
return diff;
}
// Function to print the answer
// for every query
void findAns(int arr[][2], int q)
{
precompute();
// Finding the answer for every query
for (int i = 0; i < q; i++) {
cout << "Maximum Difference: "
<< query(arr[i][0], arr[i][1])
<< endl;
cout << "Minimum Difference: "
<< minDifference(arr[i][0], arr[i][1])
<< endl;
}
}
// Driver code
int main()
{
int q = 1;
int arr[][2] = { { 21, 100 } };
findAns(arr, q);
return 0;
}
Java
// Java program to find the maximum
// differences between two Fibonacci
// numbers in given ranges
import java.util.*;
import java.lang.*;
class GFG{
static final int MAX = 100005;
static boolean isFib[] = new boolean[MAX];
static int[] prefix = new int[MAX],
suffix = new int[MAX];
// Function to precompute the Fibonacci,
// Prefix array and Suffix array
static void precompute()
{
// Variable to store the Fibonacci
// numbers
// Marking the first two Fibonacci
// numbers as True in the array
int prev = 0, curr = 1;
isFib[prev] = isFib[curr] = true;
// Loop to iterate until the
// maximum number
while (curr + prev < MAX)
{
int temp = curr + prev;
isFib[temp] = true;
prev = curr;
curr = temp;
}
prefix[1] = 1;
suffix[MAX - 1] = (int)1e9 + 7;
// Precomputing Prefix array
for(int i = 2; i < MAX; i++)
{
// If the number is a Fibonacci
// number, then adding it to the
// prefix array
if (isFib[i])
prefix[i] = i;
else
prefix[i] = prefix[i - 1];
}
// Precompute Suffix array
for(int i = MAX - 2; i > 1; i--)
{
if (isFib[i])
suffix[i] = i;
else
suffix[i] = suffix[i + 1];
}
}
// Function to solve each query
static int query(int L, int R)
{
if (prefix[R] < L || suffix[L] > R)
return 0;
else
return prefix[R] - suffix[L];
}
// Function to return the minimum
// difference between any two
// fibonacci numbers from the
// given range [L, R]
static int minDifference(int L, int R)
{
// Find the first Fibonacci numbers
// from the range
int fst = 0;
for(int i = L; i <= R; i++)
{
if (isFib[i])
{
fst = i;
break;
}
}
// Find the second Fibonacci numbers
// from the range
int snd = 0;
for(int i = fst + 1; i <= R; i++)
{
if (isFib[i])
{
snd = i;
break;
}
}
// If the number of fibonacci
// numbers in the given range is < 2
if (snd == 0)
return -1;
// To store the minimum difference
// between two consecutive fibonacci
// numbers from the range
int diff = snd - fst;
// Range left to check for
// fibonacci numbers
int left = snd + 1;
int right = R;
// For every integer in the range
for(int i = left; i <= right; i++)
{
// If the current integer is fibonacci
if (isFib[i])
{
// If the difference between i
// and snd is minimum so far
if (i - snd <= diff)
{
fst = snd;
snd = i;
diff = snd - fst;
}
}
}
return diff;
}
// Function to print the answer
// for every query
static void findAns(int arr[][], int q)
{
precompute();
// Finding the answer for every query
for(int i = 0; i < q; i++)
{
System.out.println("Maximum Difference: " +
query(arr[i][0], arr[i][1]));
System.out.println("Minimum Difference: " +
minDifference(arr[i][0], arr[i][1]));
}
}
// Driver code
public static void main(String[] args)
{
int q = 1;
int arr[][] = { { 21, 100 } };
findAns(arr, q);
}
}
// This code is contributed by offbeat
Python3
# Python3 program to find the maximum differences
# between two Fibonacci numbers in given ranges
MAX = 100005
isFib = [False]*MAX
prefix = [0]*MAX
suffix = [0]*MAX
# Function to precompute the Fibonacci,
# Prefix array and Suffix array
def precompute():
# Marking the first two Fibonacci numbers
# as True in the array
prev , curr = 0 , 1
isFib[prev] = True
isFib[curr] = True
# Loop to iterate until the maximum number
while (curr < MAX):
temp = curr + prev
if temp R):
return 0
else:
return prefix[R] - suffix[L]
# Function to return the minimum difference
# between any two fibonacci numbers
# from the given range [L, R]
def minDifference(L, R):
# Find the first Fibonacci numbers
# from the range
fst = 0
for i in range(L, R + 1):
if (isFib[i]):
fst = i
break
# Find the second Fibonacci numbers
# from the range
snd = 0
for i in range(fst + 1, R + 1 ):
if (isFib[i]):
snd = i
break
# If the number of fibonacci numbers in
# the given range is < 2
if (snd == 0):
return -1
# To store the minimum difference between
# two consecutive fibonacci numbers from the range
diff = snd - fst
# Range left to check for fibonacci numbers
left = snd + 1
right = R
# For every integer in the range
for i in range(left, right + 1):
# If the current integer is fibonacci
if (isFib[i]):
# If the difference between i
# and snd is minimum so far
if (i - snd <= diff):
fst = snd
snd = i
diff = snd - fst
return diff
# Function to print the answer
# for every query
def findAns(arr, q):
precompute()
# Finding the answer for every query
for i in range(q):
print( "Maximum Difference: "
, query(arr[i][0], arr[i][1]))
print("Minimum Difference: "
, minDifference(arr[i][0], arr[i][1]))
# Driver code
if __name__ == "__main__":
q = 1
arr = [ [ 21, 100 ] ]
findAns(arr, q)
# This code is contributed by chitranayal
输出:
Maximum Difference: 68
Minimum Difference: 13