isograms

t11e1.isograms.cpp

// t11e10.isograms.cpp
// juanfc 2023-11-22
// https://gist.github.com/juanfal/1b181c7c25d6af7288678d09a6c5ccae

#include <iostream>
#include <array>
using namespace std;

typedef array<int,256> TCharFreq;

void test(string s);

int main()
{
    test("Dermatoglyphics" );
    test("aba" );
    test("moOse" );
    return 0;
}

bool isIsogram(string s);
void test(string s)
{
    if (isIsogram(s))
        cout << s << " IS isogram" << endl;
    else
        cout << s << " is NOT isogram" << endl;
}

TCharFreq getFreqs(string s);

bool isIsogram(string s)
{
    TCharFreq f = getFreqs(s);
    int i = 0;
    while (i < 256 and f[i] < 2)
        ++i;
    return i == 256;
}

char toLow(char c);
TCharFreq getFreqs(string s)
{
    TCharFreq r;
    for (int i = 0; i < 256; ++i)
        r[i] = 0;

    for (int i = 0; i < s.length(); ++i)
        ++r[toLow(s[i])];
    return r;
}
char toLow(char c)
{
    char r = c;
    if ('A' <= c and c <= 'Z')
        r = c + 'a'-'A';
    return r;
}