I have array contains strings. I have to read the words one by one and output words which has any character in it appearing exactly two times. But my code also show 3 or more same character also. How can I output the words which only character appearing two times ? For example not showing : "aaaa" or "aaab"
const words = [
"asdf",
"fdas",
"asds",
"d fm",
"dfaa",
"aaaa",
"aabb",
"aaabb"
];
function checkString(text,index){
if((text.length - index) == 0 ){ //stop condition
return false;
}else{
return checkString(text,index + 1)
|| text.substr(0, index).indexOf(text[index])!=-1;
}
}
// example Data to test
for(var idx in words){
var txt = words[idx];
if(checkString(txt,0)) {
console.log(txt);
}
}const words = [
"asdf",
"fdas",
"asds",
"d fm",
"dfaa",
"aaaa",
"aabb",
"aaabb"
];
/*
Output have to be :
asds
dfaa
aabb
aaabb
*/
const words = [ "asdf", "fdas", "asds", "d fm", "dfaa", "aaaa", "aabb", "aaabb" ];
function checkString(text) {
//create a map to store the frequency of characters
let map = new Map();
for(let ch of text){
if(map.has(ch)){
map.set(ch, map.get(ch)+1);
}else{
map.set(ch, 1);
}
}
//now check if frequency of any character is equal to 2
return [...map.values()].some(x => x == 2);
}
// example Data to test
for (let txt of words) {
if (checkString(txt)) {
console.log(txt);
}
}You can build an object mapping letters in your input string to its occurrences in it, then filter the letters based on whether they appear twice:
const checkString = (inputString) => {
// Build an empty object
const occurrences = {};
for (let char of inputString) {
// For each character in the input string, add one to its occurrence count
// If it has never appeared until now, occurrences[char] + 1 will evaluate
// to NaN, and Nan || 1 is 1
occurrences[char] = occurrences[char] + 1 || 1;
}
// Get the characters appearing in the string
const charsInInputString = Object.keys(occurrences);
// Extract only the characters appearing exactly twice
const charsAppearingTwice = charsInInputString.filter(
(char) => occurrences[char] === 2
);
// Return true if there is at least one such character
return charsAppearingTwice.length > 0;
};
Your final array of correct words would then be words.filter(checkString).
If you want to format the words to display as a single string, with a space separator, you can use the .join method:
const checkedWords = words.filter(checkString).join(" "); // = asds dfaa aabb aaabb
A better way to do it is to write a function that takes a string and counts how many of each character it contains, and then check if there's a character that appears exactly two times.
Something along the lines of
function checkString(text){
const charAppearances = {};
text.split('').forEach( character => {
charAppearances[character] = (charAppearances[character] || 0) + 1
})
return Object.values(charAppearances).includes(2);
}
The purpose of charAppearances is to count how many times a character appears, so for example for the string 'asdf' it will be {a: 1, s: 1, d:1, f:1}
The forEach section iterates over the characters of the string and updates the count of the current character (The charAppearances[character] = (charAppearances[character] || 0) + 1 means "If character exists in charAppearances, add 1 to it, otherwise add 1 to 0, which will result 1)