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

1.3.cpp

#include<iostream>

using namespace std;

unsigned const NUM_CHAR = 256;

bool isPermutation1(string str1, string str2)
{
    sort(str1.begin(), str1.end());
    sort(str2.begin(), str2.end());
    return str1 == str2;
}

bool isPermutation2(string str1, string str2)
{
    if (str1.size() != str2.size()) return false;
    
    int a[NUM_CHAR]{};
    
    for (char c : str1) a[c]++;
    
    for (char c : str2) {
        if (--a[c] < 0) return false;
    }
    
    return true;
}

int main(int argc, char *argv[])
{
    cout << isPermutation1("31", "13") << endl;
    return 0;
}