cluster-bottom-up.js

const a = [0,[[2,[3,3]],[[3,[4,4]],[3,[4,[[6,6],5]]]]]]


const findBranchSize = R.pipe(R.flatten, R.length)

const compareBranches = R.useWith(R.gte, [findBranchSize, findBranchSize])

const findDeepestNode = (tree) => {
  let i = 0;
  let path = [];
  let currentBranch = tree
  while((R.length(currentBranch[0]) || R.length(currentBranch[1]))) {
    let deepestIndex = compareBranches(currentBranch[0], currentBranch[1]) ? 0 : 1; 
    path.push(deepestIndex)
    currentBranch = currentBranch[deepestIndex] 
    i++
  }
  return path
}


const data =  [
  { id: 1, size: 20 },
  [
    [
      { id: 2, size: 19 },
      [    
        [
          { id: 3, size: 16 },
          [
            [
              { id: 4, size: 5 },
              [
                [
                  { id: 5, size: 3 },
                  [
                    { id: 6, size: 3 },
                    [
                      { id: 7, size: 18 },
                      { id: 8, size: 17 }
                    ]
                  ]
                ],
                { id: 9, size: 12 }
              ]
            ],
            [
              { id: 13, size: 3 },
              [
                [
                  { id: 17, size: 3 },
                  [
                    { id: 18, size: 3 },
                    [
                      { id: 19, size: 18 },
                      { id: 20, size: 17 }
                    ]
                  ]
                ],
                [
                  { id: 15, size: 18 },
                  { id: 16, size: 17 }
                ]
              ]
            ],
          ]
        ],
        { id: 11, size: 13 }
      ]
    ],
    { id: 12, size: 7 }
  ]
];



const checkCluster = R.pipe(R.flatten, R.map(R.prop('size')), R.sum, R.gte(40))

const splitTreeBranches = tree => {
  const clusters = []
  let currentTree = tree;
  let i = 0;
  while(currentTree && (i < 5)) {
    if (checkCluster([currentTree])) {
      clusters.push(currentTree)
      currentTree = null;
    } else {
      console.log(currentTree)
      let path = findDeepestNode(currentTree)
 
      let currentBranch = R.path(path)(currentTree)
      let j = 0;
      let lastPath, lastBranch;
      while(checkCluster([currentBranch]) && j < 10) {
        lastPath = path
        lastBranch = currentBranch
        path = R.init(path);
        currentBranch = R.path(path)(currentTree)
      }  
      clusters.push(flatten([lastBranch]))
      currentTree = R.dissocPath(lastPath)(currentTree)  
    }
    i++;
  }
  return clusters
} 

splitTreeBranches(data)