Question

How to find the starting and ending position of a given value in a sorted integer array in JavaScript

Answer 1

function findStartingEndingPosition(arr, value) {
    let result = Array(2).fill(-1);

    let i = 0;
    
    for (;i < arr.length - 1; i++) {
        if (arr[i] == value) {
            result[0] = i;
            result[1] = i;
            break;
        }
    }
    
    for (let j = i; j < arr.length - 1; j++) {
        if (arr[j] == arr[j + 1]) {
            result[1] = j + 1;
        }
        else {
            break;
        }
    }
    
    return result;
}
        
const arr = [1, 3, 4, 7, 7, 8, 8, 8, 10, 11];
const value = 8;

const result = findStartingEndingPosition(arr, value);

console.log("start: " + result[0]);
console.log("end: " + result[1]);



/*
run:

start: 5
end: 7

*/

 

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Answer 2

function findStartingEndingPosition(arr, value) {
    let result = Array(2).fill(-1);

    for (let i = 0; i < arr.length; i++) {
        if (arr[i] !== value) {
            continue;
        }

        if (result[0] === -1) {
            result[0] = i;
        }
        
        result[1] = i;
    }

    return result;
}
        
const arr = [1, 3, 4, 7, 7, 8, 8, 8, 10, 11];
const value = 8;

const result = findStartingEndingPosition(arr, value);

console.log("start: " + result[0]);
console.log("end: " + result[1]);



/*
run:

start: 5
end: 7

*/

 

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