1394-Find_Lucky_Integer_in_an_Array.js

// 60ms, 97.75%
// 42.4 MB

const findLucky = function(arr) {
    let result = -1;
    const freq = {};
    
    for(let i = 0; i < arr.length; i++) {
        const num = arr[i];
        freq[num] = freq[num] ? freq[num] + 1 : 1;
    }

    for(const [key, value] of Object.entries(freq)) {
        if(+key === value) result = value;
    }

    return result;
};

console.log(findLucky([2,2,3,4]));

console.log(findLucky([1,2,2,3,3,3]));

console.log(findLucky([2,2,2,3,3]));