打印数组A[]
中的所有字符串,数组B[]
中的所有字符串都是它的子序列
给定两个由字符串组成的数组A[]
和B[]
,任务是从数组A[]
中打印所有字符串都位于B[]
作为子序列。
示例:
输入:
A[] = {"geeksforgeeks", "mapple", "twitter", "table", "Linkedin"}, B [] = {"e", "l"}
输出:
maplet tablelinkedin
说明:字符串
e
和l
都是"mapple"
,"table"
,"linkedin"
中的子集。输入:
A[] = {"geeksforgeeks", "topcoder", "leetcode"}, B [] = {"geek", "ee"}
输出:
geeksforgeeks
说明:
B[] = {"geek", "ee"}
中的每个字符串仅出现在"geeksforgeeks"
。
朴素的方法:
解决该问题的最简单方法是遍历数组A[]
,对于每个字符串,检查数组B[]
中的所有字符串是否都以子序列的形式存在。
时间复杂度:O(N ^ 2 * L)
,其中length
表示数组A[]
中字符串的最大长度
辅助空间:O(1)
。
有效方法:
要优化上述方法,请按照以下步骤操作:
-
初始化矩阵
A_fre[][]
,其中A_fre[i]
将存储第i
个字符串中的每个字符的频率。 -
初始化
B_fre[]
,以将所有字符的频率存储在数组B[]
中。 -
遍历数组
A[]
,对于每个字符串,检查数组B[]
的字符串中的字符是否比A[]
中的字符串i
的频率更高。如果
A_fre[i][j] < B_fre[j]
,其中:A_fre[i][j]
:A[i]
中 ASCII 值为('a' + j
)的字符的频率。B_fre[i][j]
:B[i]
中 ASCII 值为('a' + j
)的字符的频率。那么该字符串在
B[]
中至少有一个字符串,而不是其子序列。 -
如果
A[]
中的任何字符串的所有字符都不满足上述条件,请将该字符串打印为答案。 -
在检查了
A[]
中的所有字符串后,如果没有发现将B[]
中的所有字符串作为其适当子集的字符串,请打印-1
。
下面是上述方法的实现:
C++
// C++ Program to implement the
// above approach
#include <bits/stdc++.h>
using namespace std;
// Function to find strings from A[]
// having all strings in B[] as subsequence
void UniversalSubset(vector<string> A,
vector<string> B)
{
// Calculate respective sizes
int n1 = A.size();
int n2 = B.size();
// Stores the answer
vector<string> res;
// Stores the frequency of each
// character in strings of A[]
int A_fre[n1][26];
for (int i = 0; i < n1; i++) {
for (int j = 0; j < 26; j++)
A_fre[i][j] = 0;
}
// Compute the frequencies
// of characters of all strings
for (int i = 0; i < n1; i++) {
for (int j = 0; j < A[i].size();
j++) {
A_fre[i][A[i][j] - 'a']++;
}
}
// Stores the frequency of each
// character in strings of B[]
// each character of a string in B[]
int B_fre[26] = { 0 };
for (int i = 0; i < n2; i++) {
int arr[26] = { 0 };
for (int j = 0; j < B[i].size();
j++) {
arr[B[i][j] - 'a']++;
B_fre[B[i][j] - 'a']
= max(B_fre[B[i][j] - 'a'],
arr[B[i][j] - 'a']);
}
}
for (int i = 0; i < n1; i++) {
int flag = 0;
for (int j = 0; j < 26; j++) {
// If the frequency of a character
// in B[] exceeds that in A[]
if (A_fre[i][j] < B_fre[j]) {
// A string exists in B[] which
// is not a proper subset of A[i]
flag = 1;
break;
}
}
// If all strings in B[] are
// proper subset of A[]
if (flag == 0)
// Push the string in
// resultant vector
res.push_back(A[i]);
}
// If any string is found
if (res.size()) {
// Print those strings
for (int i = 0; i < res.size();
i++) {
for (int j = 0; j < res[i].size();
j++)
cout << res[i][j];
}
cout << " ";
}
// Otherwise
else
cout << "-1";
}
// Driver code
int main()
{
vector<string> A = { "geeksforgeeks",
"topcoder",
"leetcode" };
vector<string> B = { "geek", "ee" };
UniversalSubset(A, B);
return 0;
}
Java
// Java program to implement
// the above approach
import java.util.*;
class GFG {
// Function to find strings from A[]
// having all strings in B[] as subsequence
static void UniversalSubset(List<String> A,
List<String> B)
{
// Calculate respective sizes
int n1 = A.size();
int n2 = B.size();
// Stores the answer
List<String> res = new ArrayList<>();
// Stores the frequency of each
// character in strings of A[]
int[][] A_fre = new int[n1][26];
for(int i = 0; i < n1; i++)
{
for(int j = 0; j < 26; j++)
A_fre[i][j] = 0;
}
// Compute the frequencies
// of characters of all strings
for(int i = 0; i < n1; i++)
{
for(int j = 0; j < A.get(i).length(); j++)
{
A_fre[i][A.get(i).charAt(j) - 'a']++;
}
}
// Stores the frequency of each
// character in strings of B[]
// each character of a string in B[]
int[] B_fre = new int[26];
for(int i = 0; i < n2; i++)
{
int[] arr = new int[26] ;
for(int j = 0; j < B.get(i).length(); j++)
{
arr[B.get(i).charAt(j) - 'a']++;
B_fre[B.get(i).charAt(j) - 'a'] = Math.max(
B_fre[B.get(i).charAt(j) - 'a'],
arr[B.get(i).charAt(j) - 'a']);
}
}
for(int i = 0; i < n1; i++)
{
int flag = 0;
for(int j = 0; j < 26; j++)
{
// If the frequency of a character
// in B[] exceeds that in A[]
if (A_fre[i][j] < B_fre[j])
{
// A string exists in B[] which
// is not a proper subset of A[i]
flag = 1;
break;
}
}
// If all strings in B[] are
// proper subset of A[]
if (flag == 0)
// Push the string in
// resultant vector
res.add(A.get(i));
}
// If any string is found
if (res.size() != 0)
{
// Print those strings
for(int i = 0; i < res.size(); i++)
{
for(int j = 0;
j < res.get(i).length();
j++)
System.out.print(res.get(i).charAt(j));
}
System.out.print(" ");
}
// Otherwise
else
System.out.print("-1");
}
// Driver code
public static void main (String[] args)
{
List<String> A = Arrays.asList("geeksforgeeks",
"topcoder",
"leetcode");
List<String> B = Arrays.asList("geek", "ee");
UniversalSubset(A, B);
}
}
// This code is contributed by offbeat
Python3
# Python3 program to implement
# the above approach
# Function to find strings from A[]
# having all strings in B[] as subsequence
def UniversalSubset(A, B):
# Calculate respective sizes
n1 = len(A)
n2 = len(B)
# Stores the answer
res = []
# Stores the frequency of each
# character in strings of A[]
A_freq = [[0 for x in range(26)]
for y in range(n1)]
# Compute the frequencies
# of characters of all strings
for i in range(n1):
for j in range(len(A[i])):
A_freq[i][ord(A[i][j]) - ord('a')] += 1
# Stores the frequency of each
# character in strings of B[]
# each character of a string in B[]
B_freq = [0] * 26
for i in range(n2):
arr = [0] * 26
for j in range(len(B[i])):
arr[ord(B[i][j]) - ord('a')] += 1
B_freq[ord(B[i][j]) - ord('a')] = max(
B_freq[ord(B[i][j]) - ord('a')],
arr[ord(B[i][j]) - ord('a')])
for i in range(n1):
flag = 0
for j in range(26):
# If the frequency of a character
# in B[] exceeds that in A[]
if(A_freq[i][j] < B_freq[j]):
# A string exists in B[] which
# is not a proper subset of A[i]
flag = 1
break
# If all strings in B[] are
# proper subset of A[]
if(flag == 0):
# Push the string in
# resultant vector
res.append(A[i])
# If any string is found
if(len(res)):
# Print those strings
for i in range(len(res)):
for j in range(len(res[i])):
print(res[i][j], end = "")
# Otherwise
else:
print(-1, end = "")
# Driver code
if __name__ == '__main__':
A = [ "geeksforgeeks", "topcoder",
"leetcode" ]
B = [ "geek", "ee" ]
UniversalSubset(A, B)
# This code is contributed by Shivam Singh
C
// C# program to implement
// the above approach
using System;
using System.Collections.Generic;
class GFG{
// Function to find strings from []A
// having all strings in []B as subsequence
static void UniversalSubset(List<String> A,
List<String> B)
{
// Calculate respective sizes
int n1 = A.Count;
int n2 = B.Count;
// Stores the answer
List<String> res = new List<String>();
// Stores the frequency of each
// character in strings of []A
int[,] A_fre = new int[n1, 26];
for(int i = 0; i < n1; i++)
{
for(int j = 0; j < 26; j++)
A_fre[i, j] = 0;
}
// Compute the frequencies
// of characters of all strings
for(int i = 0; i < n1; i++)
{
for(int j = 0; j < A[i].Length; j++)
{
A_fre[i, A[i][j] - 'a']++;
}
}
// Stores the frequency of each
// character in strings of []B
// each character of a string in []B
int[] B_fre = new int[26];
for(int i = 0; i < n2; i++)
{
int[] arr = new int[26];
for(int j = 0; j < B[i].Length; j++)
{
arr[B[i][j] - 'a']++;
B_fre[B[i][j] - 'a'] = Math.Max(
B_fre[B[i][j] - 'a'],
arr[B[i][j] - 'a']);
}
}
for(int i = 0; i < n1; i++)
{
int flag = 0;
for(int j = 0; j < 26; j++)
{
// If the frequency of a character
// in []B exceeds that in []A
if (A_fre[i, j] < B_fre[j])
{
// A string exists in []B which
// is not a proper subset of A[i]
flag = 1;
break;
}
}
// If all strings in []B are
// proper subset of []A
if (flag == 0)
// Push the string in
// resultant vector
res.Add(A[i]);
}
// If any string is found
if (res.Count != 0)
{
// Print those strings
for(int i = 0; i < res.Count; i++)
{
for(int j = 0; j < res[i].Length; j++)
Console.Write(res[i][j]);
}
Console.Write(" ");
}
// Otherwise
else
Console.Write("-1");
}
// Driver code
public static void Main(String[] args)
{
List<String> A = new List<String>();
A.Add("geeksforgeeks");
A.Add("topcoder");
A.Add("leetcode");
List<String> B = new List<String>();
B.Add("geek");
B.Add("ee");
UniversalSubset(A, B);
}
}
// This code is contributed by amal kumar choubey
输出:
geeksforgeeks
时间复杂度:O(N * L)
,其中length
表示数组A[]
中字符串的最大长度。
辅助空间:O(n)
。
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