给定一个字符串str和Q查询。每个查询包含一个整数K。任务是找到为每个查询选择任意长度的K个相等子字符串的方法数量。请注意，K个子串的集合必须是唯一的。
例子：
Input: str = “aabaab”, que[] = {3}
Output: 4
“a” is the only sub-string that appears more than 3 times i.e. 4.
And there are 4 ways of choosing 3 different strings from the given 4 strings.
Input: str = “aggghh”, que[] = {1, 2, 3}
Output:
21
5
1
方法：可以按照以下步骤解决问题并在尽可能短的时间内回答每个查询。
- 生成一个字符串的所有子字符串，并使用哈希计算每个唯一子字符串的出现次数。
- 对于每个查询，答案将选择出现超过K次(例如X)的每个字符串的K个子字符串。答案将是
- 可以通过预先计算二项式系数来降低每个查询的时间复杂度
下面是上述方法的实现：
C++
// C++ implementation of the approach
#include
using namespace std;
#define maxlen 100
// Function to generate all the sub-strings
void generateSubStrings(string s, unordered_map& mpp)
{
// Length of the string
int l = s.length();
// Generate all sub-strings
for (int i = 0; i < l; i++) {
string temp = "";
for (int j = i; j < l; j++) {
temp += s[j];
// Count the occurrence of
// every sub-string
mpp[temp] += 1;
}
}
}
// Compute the Binomial Coefficient
void binomialCoeff(int C[maxlen][maxlen])
{
int i, j;
// Calculate value of Binomial Coefficient
// in bottom up manner
for (i = 0; i < 100; i++) {
for (j = 0; j < 100; j++) {
// Base Cases
if (j == 0 || j == i)
C[i][j] = 1;
// Calculate value using previously
// stored values
else
C[i][j] = C[i - 1][j - 1] + C[i - 1][j];
}
}
}
// Function to return the result for a query
int answerQuery(unordered_map& mpp,
int C[maxlen][maxlen], int k)
{
int ans = 0;
// Iterate for every
// unique sub-string
for (auto it : mpp) {
// Count the combinations
if (it.second >= k)
ans += C[it.second][k];
}
return ans;
}
// Driver code
int main()
{
string s = "aabaab";
// Get all the sub-strings
// Store the occurrence of
// all the sub-strings
unordered_map mpp;
generateSubStrings(s, mpp);
// Pre-computation
int C[maxlen][maxlen];
memset(C, 0, sizeof C);
binomialCoeff(C);
// Queries
int queries[] = { 2, 3, 4 };
int q = sizeof(queries) / sizeof(queries[0]);
// Perform queries
for (int i = 0; i < q; i++)
cout << answerQuery(mpp, C, queries[i]) << endl;
return 0;
} Java
// Java implementation of the approach
import java.util.HashMap;
class GFG
{
static int maxlen = 100;
// Function to generate all the sub-strings
public static void generateSubStrings(
String s, HashMap mpp)
{
// Length of the string
int l = s.length();
// Generate all sub-strings
for (int i = 0; i < l; i++)
{
String temp = "";
for (int j = i; j < l; j++)
{
temp += s.charAt(j);
// Count the occurrence of
// every sub-string
if (mpp.containsKey(temp))
{
int x = mpp.get(temp);
mpp.put(temp, ++x);
}
else
mpp.put(temp, 1);
}
}
}
// Compute the Binomial Coefficient
public static void binomialCoeff(int[][] C)
{
int i, j;
// Calculate value of Binomial Coefficient
// in bottom up manner
for (i = 1; i < 100; i++)
{
for (j = 0; j < 100; j++)
{
// Base Cases
if (j == 0 || j == i)
C[i][j] = 1;
// Calculate value using previously
// stored values
else
C[i][j] = C[i - 1][j - 1] +
C[i - 1][j];
}
}
}
// Function to return the result for a query
public static int answerQuery(HashMap mpp,
int[][] C, int k)
{
int ans = 0;
// Iterate for every
// unique sub-string
for (HashMap.Entry entry : mpp.entrySet())
{
// Count the combinations
if (entry.getValue() >= k)
ans += C[entry.getValue()][k];
}
return ans;
}
// Driver code
public static void main(String[] args)
{
String s = "aabaab";
// Get all the sub-strings
// Store the occurrence of
// all the sub-strings
HashMap mpp = new HashMap<>();
generateSubStrings(s, mpp);
// Pre-computation
int[][] C = new int[maxlen][maxlen];
binomialCoeff(C);
// Queries
int[] queries = { 2, 3, 4 };
int q = queries.length;
// Perform queries
for (int i = 0; i < q; i++)
System.out.println(answerQuery(mpp, C,
queries[i]));
}
}
// This code is contributed by
// sanjeev2552 Python3
# Python3 implementation of the approach
from collections import defaultdict
maxlen = 100
# Function to generate all the sub-strings
def generateSubStrings(s, mpp):
# Length of the string
l = len(s)
# Generate all sub-strings
for i in range(0, l):
temp = ""
for j in range(i, l):
temp += s[j]
# Count the occurrence of
# every sub-string
mpp[temp] += 1
# Compute the Binomial Coefficient
def binomialCoeff(C):
# Calculate value of Binomial
# Coefficient in bottom up manner
for i in range(0, 100):
for j in range(0, 100):
# Base Cases
if j == 0 or j == i:
C[i][j] = 1
# Calculate value using previously
# stored values
else:
C[i][j] = C[i - 1][j - 1] + C[i - 1][j]
# Function to return the result for a query
def answerQuery(mpp, C, k):
ans = 0
# Iterate for every
# unique sub-string
for it in mpp:
# Count the combinations
if mpp[it] >= k:
ans += C[mpp[it]][k]
return ans
# Driver code
if __name__ == "__main__":
s = "aabaab"
# Get all the sub-strings
# Store the occurrence of
# all the sub-strings
mpp = defaultdict(lambda:0)
generateSubStrings(s, mpp)
# Pre-computation
C = [[0 for i in range(maxlen)]
for j in range(maxlen)]
binomialCoeff(C)
# Queries
queries = [2, 3, 4]
q = len(queries)
# Perform queries
for i in range(0, q):
print(answerQuery(mpp, C, queries[i]))
# This code is contributed by Rituraj JainC#
// C# code to print level order
// traversal in sorted order
using System;
using System.Collections.Generic;
class GFG
{
static int maxlen = 100;
// Function to generate all the sub-strings
public static void generateSubStrings(String s,
Dictionary mpp)
{
// Length of the string
int l = s.Length;
// Generate all sub-strings
for (int i = 0; i < l; i++)
{
String temp = "";
for (int j = i; j < l; j++)
{
temp += s[j];
// Count the occurrence of
// every sub-string
if (mpp.ContainsKey(temp))
{
mpp[temp] = ++mpp[temp];
}
else
mpp.Add(temp, 1);
}
}
}
// Compute the Binomial Coefficient
public static void binomialCoeff(int[,] C)
{
int i, j;
// Calculate value of Binomial Coefficient
// in bottom up manner
for (i = 1; i < 100; i++)
{
for (j = 0; j < 100; j++)
{
// Base Cases
if (j == 0 || j == i)
C[i, j] = 1;
// Calculate value using previously
// stored values
else
C[i, j] = C[i - 1, j - 1] +
C[i - 1, j];
}
}
}
// Function to return the result for a query
public static int answerQuery(Dictionary mpp,
int[,] C, int k)
{
int ans = 0;
// Iterate for every
// unique sub-string
foreach(KeyValuePair entry in mpp)
{
// Count the combinations
if (entry.Value >= k)
ans += C[entry.Value, k];
}
return ans;
}
// Driver code
public static void Main(String[] args)
{
String s = "aabaab";
// Get all the sub-strings
// Store the occurrence of
// all the sub-strings
Dictionary mpp = new Dictionary();
generateSubStrings(s, mpp);
// Pre-computation
int[,] C = new int[maxlen, maxlen];
binomialCoeff(C);
// Queries
int[] queries = { 2, 3, 4 };
int q = queries.Length;
// Perform queries
for (int i = 0; i < q; i++)
Console.WriteLine(answerQuery(mpp, C,
queries[i]));
}
}
// This code is contributed by 29AjayKumar 输出：
10
4
1