code.js

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    A = new Set(A)
    A = [...A]
    A = A.sort(function(a,b){return a-b})
    var check = true
    
    if (A.length == 1 && A[0] != 1) return 1
    
    for (var i = 0, len = A.length; i < len; i++) {
        if (A[i] > 0) {
            if (check && A[i] != 1) return 1
            if (A[i] + 1 != A[i + 1]) return A[i] + 1
            check = false 
        }
    }
    
    return 1
}




function solution(X, A) {
    
    var arr = []
    var range = Math.abs(X - A[0])
    var check = 0
    var arrLength = 0
    
    if (A.length == 0) {
        return -1
    }
    
    if (X == 1 && A[0] == 1) {
        return 0
    }
    
    for (var i = 0; i < range; i++) {
        arr.push(A[0] + i)
    }
    
    arrLength = arr.length
    
    for (var i = 1; i < A.length; i++) {
        if (X == A[i]) {
            if (check == arrLength && check != 0) {
                return i
            }
        }
        if (arr.includes(A[i])) {
            arr.splice(A[i]-1, 1)
            check += 1
        }
    }
    
    return -1
}


function solution(A) {
    // write your code in JavaScript (Node.js 8.9.4)
    A = new Set(A)
    A = [...A]
    A = A.sort(function(a,b){return a-b})
    var check = true
    
    for(var i = 0; i < A.length; i++) {
        if(A[i] > 0) {
            if(A[i] != 1 && check) {
                return 1
            }
            if(A[i] + 1 != A[i + 1]) {
                return A[i] + 1
            }
            check = false
        }
    }
    
    return 1
}

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(N, A) {
    // write your code in JavaScript (Node.js 8.9.4)
    var lastMax = 0;
    var max = 0; 
    var counters = new Array (N);
    for(j = 0; j < N; j++) counters[j] = 0;
    
    for(var j=0; j < A.length; j++){
        if(A[j] < N + 1){
            i = A[j] - 1;
            if (counters[i] < lastMax) {
                counters[i] = lastMax;
            }
            counters[i]++;
            if (max < counters[i]) {
                max = counters[i]; // max = 1
            }
        } else {
            lastMax = max;
        }
    }
    
    for(var j = 0; j < N; j++){
      if (counters[j] < lastMax) {
          counters[j] = lastMax;
      }
    }
    
    return counters;
}