README_EN.md

01.02. Check Permutation

中文文档

Description

Given two strings,write a method to decide if one is a permutation of the other.

Example 1:

Input: s1 = "abc", s2 = "bca"

Output: true

Example 2:

Input: s1 = "abc", s2 = "bad"

Output: false

Note:

1. 0 <= len(s1) <= 100
2. 0 <= len(s2) <= 100

Solutions

Python3

class Solution:
    def CheckPermutation(self, s1: str, s2: str) -> bool:
        return Counter(s1) == Counter(s2)

class Solution:
    def CheckPermutation(self, s1: str, s2: str) -> bool:
        return sorted(s1) == sorted(s2)

Java

class Solution {
    public boolean CheckPermutation(String s1, String s2) {
        if (s1.length() != s2.length()) {
            return false;
        }
        int[] cnt = new int[26];
        for (char c : s1.toCharArray()) {
            ++cnt[c - 'a'];
        }
        for (char c : s2.toCharArray()) {
            if (--cnt[c - 'a'] < 0) {
                return false;
            }
        }
        return true;
    }
}

class Solution {
    public boolean CheckPermutation(String s1, String s2) {
        char[] cs1 = s1.toCharArray();
        char[] cs2 = s2.toCharArray();
        Arrays.sort(cs1);
        Arrays.sort(cs2);
        return Arrays.equals(cs1, cs2);
    }
}

C++

class Solution {
public:
    bool CheckPermutation(string s1, string s2) {
        if (s1.size() != s2.size()) return false;
        int cnt[26] = {0};
        for (char & c : s1) ++cnt[c - 'a'];
        for (char & c : s2) if (--cnt[c - 'a'] < 0) return false;
        return true;
    }
};

class Solution {
public:
    bool CheckPermutation(string s1, string s2) {
        sort(s1.begin(), s1.end());
        sort(s2.begin(), s2.end());
        return s1 == s2;
    }
};

Go

func CheckPermutation(s1 string, s2 string) bool {
	if len(s1) != len(s2) {
		return false
	}
	cnt := make([]int, 26)
	for _, c := range s1 {
		cnt[c-'a']++
	}
	for _, c := range s2 {
		cnt[c-'a']--
		if cnt[c-'a'] < 0 {
			return false
		}
	}
	return true
}

func CheckPermutation(s1 string, s2 string) bool {
	cs1, cs2 := []byte(s1), []byte(s2)
	sort.Slice(cs1, func(i, j int) bool { return cs1[i] < cs1[j] })
	sort.Slice(cs2, func(i, j int) bool { return cs2[i] < cs2[j] })
	return string(cs1) == string(cs2)
}

JavaScript

/**
 * @param {string} s1
 * @param {string} s2
 * @return {boolean}
 */
var CheckPermutation = function (s1, s2) {
    if (s1.length != s2.length) {
        return false;
    }
    const cnt = new Array(26).fill(0);
    for (let i = 0; i < s1.length; ++i) {
        const j = s1.codePointAt(i) - 'a'.codePointAt(0);
        ++cnt[j];
    }
    for (let i = 0; i < s2.length; ++i) {
        const j = s2.codePointAt(i) - 'a'.codePointAt(0);
        if (--cnt[j] < 0) {
            return false;
        }
    }
    return true;
};

TypeScript

function CheckPermutation(s1: string, s2: string): boolean {
    const n = s1.length;
    const m = s2.length;
    if (n !== m) {
        return false;
    }
    const map = new Map<string, number>();
    for (let i = 0; i < n; i++) {
        map.set(s1[i], (map.get(s1[i]) ?? 0) + 1);
        map.set(s2[i], (map.get(s2[i]) ?? 0) - 1);
    }
    for (const v of map.values()) {
        if (v !== 0) {
            return false;
        }
    }
    return true;
}

function CheckPermutation(s1: string, s2: string): boolean {
    return [...s1].sort().join('') === [...s2].sort().join('');
}

Rust

use std::collections::HashMap;
impl Solution {
    pub fn check_permutation(s1: String, s2: String) -> bool {
        let n = s1.len();
        let m = s2.len();
        if n != m {
            return false;
        }
        let s1 = s1.as_bytes();
        let s2 = s2.as_bytes();
        let mut map = HashMap::new();
        for i in 0..n {
            *map.entry(s1[i]).or_insert(0) += 1;
            *map.entry(s2[i]).or_insert(0) -= 1;
        }
        map.values().all(|i| *i == 0)
    }
}

impl Solution {
    pub fn check_permutation(s1: String, s2: String) -> bool {
        let mut s1: Vec<char> = s1.chars().collect();
        let mut s2: Vec<char> = s2.chars().collect();
        s1.sort();
        s2.sort();
        s1 == s2
    }
}

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