forevermgg/leetcode

• 👋 Hi, I’m @forevermgg
• 👀 I’m interested in Android
• 🌱 I’m currently learning C++
• 💞️ I’m looking to collaborate on ...
• 📫 By https://www.jianshu.com/u/508c24418f06 / [email protected] reach me ...

leetcode's Issues

substr

int beautifulBinaryString(string b) {
    string temp = "010";
    int count = 0;
    for (int i = 0 ; (unsigned) i + 3  <= b.size() ; i++) {
        string s = b.substr(i,3);
        cout << s  << endl;
        if (s == temp) {
            count ++;
            i = i + 2;
        }
    }
    return count;
}

最大公约数&最小公倍数

最大公因数

//辗转相除法(欧几里得算法)
int gcd(int a, int b) {
    int da = max(a,b);
    int xiao = min(a,b);
    if(da % xiao == 0)
        return xiao;
    else   
        return gcd(xiao, da % xiao); 
}

最小公倍数. 两个整数的最小公倍数等于两整数之积除以最大公约数

int lcm(int a, int b) {
     return a*b / gcd(a, b);
}

static int gcd(int a, int b){
 if(a == 0)
    return b;
    return gcd(b % a, a);
 }

static int lcm(int a, int b) {
    return a*b/gcd(a,b);
}

static long lcm(long a, long b) {
    return Math.Abs(a * b) / gcd(a, b);
}

static long gcd(long a, long b) {
    return b == 0 ? a : gcd(b, a % b);
}

二分法搜索

string twoStrings(string s1, string s2) {
    sort(s1.begin(), s1.end());
    sort(s2.begin(), s2.end());
    int count = 0;
    for (uint64_t i = 0; i < s2.length(); i++) {
        if (binary_search(s1.begin(), s1.end(), s2[i])) {
            count ++;
        } 
    }
    return count > 0 ? "YES" : "NO";
}

string twoStrings(string s1, string s2) {
    int count = 0;
    for (uint64_t i = 0; i < s2.length(); i++) {
        if (s1.find(s2[i]) != string::npos) {
            count ++;
        }
    }
    return count > 0 ? "YES" : "NO";
}

Time limit exceeded

string twoStrings(string s1, string s2) {
    int count = 0;
    for (uint64_t i = 0; i < s1.length(); i++) {
        for (uint64_t j = 0; j < s2.length(); j++) {
            if (s1[i] == s2[j]) {
                count ++;
            } 
        }
    }
    return count > 0 ? "YES" : "NO";
}

字符串反转reverse

find()&&string::npos

https://www.hackerrank.com/challenges/strong-password/problem?isFullScreen=true&h_r=next-challenge&h_v=zen

#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);
string rtrim(const string &);

/*
 * Complete the 'minimumNumber' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts following parameters:
 *  1. INTEGER n
 *  2. STRING password
 */

int minimumNumber(int n, string password) {
    string numbers = "0123456789";
    string lower_case = "abcdefghijklmnopqrstuvwxyz";
    string upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    string special_characters = "!@#$%^&*()-+";
    int a=0,b=0,c=0,d=0;
    for(auto s:password){
        if(numbers.find(s)!=string::npos){
            a=1;
        }
        else if(lower_case.find(s)!=string::npos){
            b=1;
        }
        else if(upper_case.find(s)!=string::npos){
            c=1;
        }
        else if(special_characters.find(s)!=string::npos){
            d=1;
        }
    }
    return max(6-n,4-a-b-c-d);
}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    string n_temp;
    getline(cin, n_temp);

    int n = stoi(ltrim(rtrim(n_temp)));

    string password;
    getline(cin, password);

    int answer = minimumNumber(n, password);

    fout << answer << "\n";

    fout.close();

    return 0;
}

string ltrim(const string &str) {
    string s(str);

    s.erase(
        s.begin(),
        find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
    );

    return s;
}

string rtrim(const string &str) {
    string s(str);

    s.erase(
        find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
        s.end()
    );

    return s;
}

std::count_if && isupper

https://www.hackerrank.com/challenges/camelcase/problem?isFullScreen=true
计算字符串某一种类型个数

#include <bits/stdc++.h>

using namespace std;

/*
 * Complete the 'camelcase' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts STRING s as parameter.
 */

int camelcase(string s) {
    int count = 1;
    cout =  1 + std::count_if(s.begin(), s.end(), 
    [](const auto& c) { 
        return isupper(c); 
        } 
    ) ;
    return count;
}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    string s;
    getline(cin, s);

    int result = camelcase(s);

    fout << result << "\n";

    fout.close();

    return 0;
}

stringstream

stringstream 字符串结束符号

#include <sstream>
#include <vector>
#include <iostream>
using namespace std;

vector<int> parseInts(string str) {
	// Complete this function
    vector<int> result;
    stringstream ss(str);
    char ch;
    int a;
    while (ss) {
        ss >> a >> ch;
        result.push_back(a);
    }
    return result;
}

int main() {
    string str;
    cin >> str;
    vector<int> integers = parseInts(str);
    for(int i = 0; i < integers.size(); i++) {
        cout << integers[i] << "\n";
    }
    
    return 0;
}