给定一个字符串str ,任务是找到通过将给定字符串划分为两个非空子字符串可以获得的常见非重复字符的最大计数。
例子:
Input : str = “aabbca”
Output: 2
Explanation:
Partition the string into two substrings { { str[0], … str[2] }, { str[3], …, str[5] } }
The common non-repeating characters present in both the substrings are { ‘a’, ‘b’}
Therefore, the required output is 2.
Input: str = “aaaaaaaaaa”
Output: 1
原始的方法:要解决这个问题,最简单的方法是遍历字符串中的字符,并在每一个可能的指数字符串分割成两个非空的字符串和计数的共重复字符由两个子数。打印获得的最大计数。
下面是上述方法的实现:
C++
// C++ program to implement
// the above approach
#include
using namespace std;
// Function to count maximum common non-repeating
// characters that can be obtained by partitioning
// the string into two non-empty substrings
int countCommonChar(int ind, string& S)
{
// Stores count of non-repeating characters
// present in both the substrings
int cnt = 0;
// Stores distinct characters
// in left substring
set ls;
// Stores distinct characters
// in right substring
set rs;
// Traverse left substring
for (int i = 0; i < ind; ++i) {
// Insert S[i] into ls
ls.insert(S[i]);
}
// Traverse right substring
for (int i = ind; i < S.length();
++i) {
// Insert S[i] into rs
rs.insert(S[i]);
}
// Traverse distinct characters
// of left substring
for (auto v : ls) {
// If current character is
// present in right substring
if (rs.count(v)) {
// Update cnt
++cnt;
}
}
// Return count
return cnt;
}
// Function to partition the string into
// two non-empty substrings in all possible ways
void partitionStringWithMaxCom(string& S)
{
// Stores maximum common distinct characters
// present in both the substring partitions
int ans = 0;
// Traverse the string
for (int i = 1; i < S.length(); ++i) {
// Update ans
ans = max(ans,
countCommonChar(i, S));
}
// Print count of maximum common
// non-repeating characters
cout << ans << "\n";
}
// Driver Code
int main()
{
string str = "aabbca";
partitionStringWithMaxCom(str);
return 0;
}
Java
// Java program to implement
// the above approach
import java.util.*;
class GFG{
// Function to count maximum common non-repeating
// characters that can be obtained by partitioning
// the String into two non-empty subStrings
static int countCommonChar(int ind, String S)
{
// Stores count of non-repeating characters
// present in both the subStrings
int cnt = 0;
// Stores distinct characters
// in left subString
HashSet ls = new HashSet();
// Stores distinct characters
// in right subString
HashSet rs = new HashSet();
// Traverse left subString
for (int i = 0; i < ind; ++i) {
// Insert S[i] into ls
ls.add(S.charAt(i));
}
// Traverse right subString
for (int i = ind; i < S.length();
++i) {
// Insert S[i] into rs
rs.add(S.charAt(i));
}
// Traverse distinct characters
// of left subString
for (char v : ls) {
// If current character is
// present in right subString
if (rs.contains(v)) {
// Update cnt
++cnt;
}
}
// Return count
return cnt;
}
// Function to partition the String into
// two non-empty subStrings in all possible ways
static void partitionStringWithMaxCom(String S)
{
// Stores maximum common distinct characters
// present in both the subString partitions
int ans = 0;
// Traverse the String
for (int i = 1; i < S.length(); ++i) {
// Update ans
ans = Math.max(ans,
countCommonChar(i, S));
}
// Print count of maximum common
// non-repeating characters
System.out.print(ans+ "\n");
}
// Driver Code
public static void main(String[] args)
{
String str = "aabbca";
partitionStringWithMaxCom(str);
}
}
// This code is contributed by 29AjayKumar
Python3
# Python3 program to implement
# the above approach
# Function to count maximum common
# non-repeating characters that can
# be obtained by partitioning the
# string into two non-empty substrings
def countCommonChar(ind, S):
# Stores count of non-repeating
# characters present in both the
# substrings
cnt = 0
# Stores distinct characters
# in left substring
ls = set()
# Stores distinct characters
# in right substring
rs = set()
# Traverse left substring
for i in range(ind):
# Insert S[i] into ls
ls.add(S[i])
# Traverse right substring
for i in range(ind, len(S)):
# Insert S[i] into rs
rs.add(S[i])
# Traverse distinct characters
# of left substring
for v in ls:
# If current character is
# present in right substring
if v in rs:
# Update cnt
cnt += 1
# Return count
return cnt
# Function to partition the string
# into two non-empty substrings in
# all possible ways
def partitionStringWithMaxCom(S):
# Stores maximum common distinct
# characters present in both the
# substring partitions
ans = 0
# Traverse the string
for i in range(1, len(S)):
# Update ans
ans = max(ans, countCommonChar(i, S))
# Print count of maximum common
# non-repeating characters
print(ans)
# Driver Code
if __name__ == "__main__":
string = "aabbca"
partitionStringWithMaxCom(string)
# This code is contributed by AnkThon
C#
// C# program to implement
// the above approach
using System;
using System.Collections.Generic;
class GFG{
// Function to count maximum common non-repeating
// characters that can be obtained by partitioning
// the String into two non-empty subStrings
static int countCommonChar(int ind, String S)
{
// Stores count of non-repeating characters
// present in both the subStrings
int cnt = 0;
// Stores distinct characters
// in left subString
HashSet ls = new HashSet();
// Stores distinct characters
// in right subString
HashSet rs = new HashSet();
// Traverse left subString
for(int i = 0; i < ind; ++i)
{
// Insert S[i] into ls
ls.Add(S[i]);
}
// Traverse right subString
for(int i = ind; i < S.Length; ++i)
{
// Insert S[i] into rs
rs.Add(S[i]);
}
// Traverse distinct characters
// of left subString
foreach(char v in ls)
{
// If current character is
// present in right subString
if (rs.Contains(v))
{
// Update cnt
++cnt;
}
}
// Return count
return cnt;
}
// Function to partition the String into
// two non-empty subStrings in all possible ways
static void partitionStringWithMaxCom(String S)
{
// Stores maximum common distinct characters
// present in both the subString partitions
int ans = 0;
// Traverse the String
for(int i = 1; i < S.Length; ++i)
{
// Update ans
ans = Math.Max(ans,
countCommonChar(i, S));
}
// Print count of maximum common
// non-repeating characters
Console.Write(ans + "\n");
}
// Driver Code
public static void Main(String[] args)
{
String str = "aabbca";
partitionStringWithMaxCom(str);
}
}
// This code is contributed by Amit Katiyar
Javascript
C++
// C++ program to implement
// the above approach
#include
#include
#include
using namespace std;
using namespace __gnu_cxx;
using namespace __gnu_pbds;
template
using ordered_set = tree,
rb_tree_tag, tree_order_statistics_node_update>;
// Function to count maximum common non-repeating
// characters that can be obtained by partitioning
// the string into two non-empty substrings
int countMaxCommonChar(string& S)
{
// Stores distinct characters
// of S in sorted order
ordered_set Q;
// Stores maximum common distinct characters
// present in both the partitions
int res = 0;
// Stores frequency of each
// distinct character n the string S
map freq;
// Traverse the string
for (int i = 0; i < S.length(); i++) {
// Update frequency of S[i]
freq[S[i]]++;
}
// Traverse the string
for (int i = 0; i < S.length(); i++) {
// Decreasing frequency of S[i]
freq[S[i]]--;
// If the frequency of S[i] is 0
if (!freq[S[i]]) {
// Remove S[i] from Q
Q.erase(S[i]);
}
else {
// Insert S[i] into Q
Q.insert(S[i]);
}
// Stores count of distinct
// characters in Q
int curr = Q.size();
// Update res
res = max(res, curr);
}
cout << res << "\n";
}
// Driver Code
int main()
{
string str = "aabbca";
// Function call
countMaxCommonChar(str);
return 0;
}
Java
// Java program to implement
// the above approach
import java.util.*;
class GFG{
// Function to count maximum common non-repeating
// characters that can be obtained by partitioning
// the String into two non-empty subStrings
static void countMaxCommonChar(char[] S)
{
// Stores distinct characters
// of S in sorted order
LinkedHashSet Q = new LinkedHashSet<>();
// Stores maximum common distinct characters
// present in both the partitions
int res = 1;
// Stores frequency of each
// distinct character n the String S
HashMap freq = new HashMap<>();
// Traverse the String
for(int i = 0; i < S.length; i++)
{
// Update frequency of S[i]
if (freq.containsKey(S[i]))
{
freq.put(S[i], freq.get(S[i]) + 1);
}
else
{
freq.put(S[i], 1);
}
}
// Traverse the String
for(int i = 0; i < S.length; i++)
{
// Decreasing frequency of S[i]
if (freq.containsKey(S[i]))
{
freq.put(S[i], freq.get(S[i]) - 1);
}
// If the frequency of S[i] is 0
if (!freq.containsKey(S[i]))
{
// Remove S[i] from Q
Q.remove(S[i]);
}
else
{
// Insert S[i] into Q
Q.add(S[i]);
}
// Stores count of distinct
// characters in Q
int curr = Q.size() - 1;
// Update res
res = Math.max(res, curr);
}
System.out.print(res + "\n");
}
// Driver Code
public static void main(String[] args)
{
String str = "aabbca";
// Function call
countMaxCommonChar(str.toCharArray());
}
}
// This code is contributed by aashish1995
输出
2
时间复杂度: O(N 2 )
辅助空间: O(N)
高效的方法:为了优化上述方法,其思想是使用Hashing和Ordered Set将字符串的不同字符按排序顺序存储。请按照以下步骤解决问题:
- 初始化一个变量,比如res ,通过将字符串分成两个子字符串来存储两个子字符串存在的常见不同字符的最大计数。
- 初始化一个 Map,比如mp ,以存储字符串的每个不同字符的频率。
- 初始化一个有序集,比如Q ,以按排序顺序存储字符串的不同字符。
- 遍历该字符串的字符和为每个第i个字符,递减str的频率[i]和检查,如果熔点[STR [1]的频率等于0。如果发现为 false,则从Ordered Set 中删除str[i] 。
- 否则,在有序集合中插入str[i]并更新res = max(res, X) ,其中X是有序集合中元素的计数。
- 最后,打印res的值。
下面是上述方法的实现:
C++
// C++ program to implement
// the above approach
#include
#include
#include
using namespace std;
using namespace __gnu_cxx;
using namespace __gnu_pbds;
template
using ordered_set = tree,
rb_tree_tag, tree_order_statistics_node_update>;
// Function to count maximum common non-repeating
// characters that can be obtained by partitioning
// the string into two non-empty substrings
int countMaxCommonChar(string& S)
{
// Stores distinct characters
// of S in sorted order
ordered_set Q;
// Stores maximum common distinct characters
// present in both the partitions
int res = 0;
// Stores frequency of each
// distinct character n the string S
map freq;
// Traverse the string
for (int i = 0; i < S.length(); i++) {
// Update frequency of S[i]
freq[S[i]]++;
}
// Traverse the string
for (int i = 0; i < S.length(); i++) {
// Decreasing frequency of S[i]
freq[S[i]]--;
// If the frequency of S[i] is 0
if (!freq[S[i]]) {
// Remove S[i] from Q
Q.erase(S[i]);
}
else {
// Insert S[i] into Q
Q.insert(S[i]);
}
// Stores count of distinct
// characters in Q
int curr = Q.size();
// Update res
res = max(res, curr);
}
cout << res << "\n";
}
// Driver Code
int main()
{
string str = "aabbca";
// Function call
countMaxCommonChar(str);
return 0;
}
Java
// Java program to implement
// the above approach
import java.util.*;
class GFG{
// Function to count maximum common non-repeating
// characters that can be obtained by partitioning
// the String into two non-empty subStrings
static void countMaxCommonChar(char[] S)
{
// Stores distinct characters
// of S in sorted order
LinkedHashSet Q = new LinkedHashSet<>();
// Stores maximum common distinct characters
// present in both the partitions
int res = 1;
// Stores frequency of each
// distinct character n the String S
HashMap freq = new HashMap<>();
// Traverse the String
for(int i = 0; i < S.length; i++)
{
// Update frequency of S[i]
if (freq.containsKey(S[i]))
{
freq.put(S[i], freq.get(S[i]) + 1);
}
else
{
freq.put(S[i], 1);
}
}
// Traverse the String
for(int i = 0; i < S.length; i++)
{
// Decreasing frequency of S[i]
if (freq.containsKey(S[i]))
{
freq.put(S[i], freq.get(S[i]) - 1);
}
// If the frequency of S[i] is 0
if (!freq.containsKey(S[i]))
{
// Remove S[i] from Q
Q.remove(S[i]);
}
else
{
// Insert S[i] into Q
Q.add(S[i]);
}
// Stores count of distinct
// characters in Q
int curr = Q.size() - 1;
// Update res
res = Math.max(res, curr);
}
System.out.print(res + "\n");
}
// Driver Code
public static void main(String[] args)
{
String str = "aabbca";
// Function call
countMaxCommonChar(str.toCharArray());
}
}
// This code is contributed by aashish1995
输出
2
时间复杂度: O(N * log(N))
辅助空间: O(N)
如果您想与行业专家一起参加直播课程,请参阅Geeks Classes Live