1.1 - Is Unique

Implement an algorithm to determine if a string has all unique characters. What if you cannot use additional data structures

Idea:

Use bit mask to record characters.

Algorithm:

#include <stdio.h>
#include <stdbool.h>

bool isUnique(char* testStr){
    int checker = 0;
    
    while (*testStr != '\0'){
        
        int bitIndex = *testStr - 'a';
        
        if((checker & (1 << bitIndex)) > 0){
            return false;
        }
    
        // update char
        checker = checker | (1 << bitIndex);
        testStr++;
    }
    return true;
    
}

Test:

int main(){

    char* testStr1 = "abcdertyu";
    printf("Is the string = %s unique ? %d\n ", testStr1, isUnique(testStr1));

    char* testStr2 = "abcderteu";
    printf("Is the string = %s unique ? %d\n ", testStr2, isUnique(testStr2));

    return 0;
}