continuous_increasing_sum.js

var assert = require('assert')

function maxSumIncrease(arr){
  if(arr.length === 0) return 0
  var max = arr[0]
  var sum = arr[0]
  
  for(var i = 1; i < arr.length; i++){
    if(arr[i] === arr[i - 1] + 1){
      sum += arr[i]
    }
    else{
      sum = arr[i]
    }
    max = Math.max(sum, max)
  }
  
  return max
}

assert.equal(maxSumIncrease([1,2,3,0,4,0,5,6]), 11)
assert.equal(maxSumIncrease([]), 0)
assert.equal(maxSumIncrease([-1]), -1)
assert.equal(maxSumIncrease([-1, 0, 1, 0, 2]), 2)
             
function Node(val){
  this.val = val
  this.left = null
  this.right = null
}

var a = new Node(1)
var b = new Node(2)
var c = new Node(3)
var d = new Node(0)
var e = new Node(4)
var f = new Node(0)
var g = new Node(5)
var h = new Node(6)
var x = new Node(7)
var z = new Node(9)
a.left = b
a.right = d
b.left = c
b.right = h
d.right = e
e.right = g
g.left = x
g.right = z

function maxSumIncreaseTree(root){
  if(root === null) return 0
  return helper(root, -Infinity, 0, root.val - 1)
}

function helper(root, max, sum, pre){
  
  if(root === null) return max
  
  if(root.val === pre + 1){
    sum += root.val
  }else{
    sum = root.val
  }
  max = Math.max(max, sum)

  var l = helper(root.left, max, sum, root.val)
  var r = helper(root.right, max, sum, root.val)
  
  return Math.max(l, r)
}

assert.equal(maxSumIncreaseTree(a), 9)