Data Structures: Hash Tables
12345678910111213141516171819202122232425262728293031323334353637
// Google Question
// Given an array = [2,5,1,2,3,5,1,2,4]:
// It should return 2
//Given an array = [2,1,1,2,3,5,1,2,4]:
// It should return 1
// Given an array = [2,3,4,5]:
// It should return undefined
function firstRecurringCharacter(input) {
for (let i = 0; i<input.length; i++) {
for (let j=i+1; j < input.length; j++) {
if (input[i] === input[j]) {
return input[i]
}
}
}
return undefined;
} // O(n^2)
function firstRecurringCharacter2(input) {
let map = {};
for (let i = 0; i < input.length; i++) {
if (map[input[i]] !== undefined) {
return input[i];
} else {
map[input[i]] = i;
}
}
console.log(map);
return undefined;
}
firstRecurringCharacter2([2,5,1,2,3,5,1,2,4]);
JavaScript
INFO