recommendation doesn't work correctly in special cases

[prekoa]

request:

curl  -kL -X POST -d '{"sumCpu":6, "sumMem":12, "minNodes":4, "maxNodes":5, "sameSize":false, "zones":["eu-central-1a"], "onDemandPct":100}' "localhost:9095/api/v1/recommender/alibaba/ack/eu-central-1/cluster"

response:

{
  "provider": "alibaba",
  "service": "ack",
  "region": "eu-central-1",
  "zones": [
    "eu-central-1a"
  ],
  "nodePools": [
    {
      "vm": {
        "Category": "General purpose",
        "type": "ecs.t5-lc1m2.large",
        "avgPrice": 0,
        "onDemandPrice": 0.05,
        "cpusPerVm": 2,
        "memPerVm": 4,
        "gpusPerVm": 0,
        "burst": false,
        "networkPerf": "0.4 Gbit/s",
        "networkPerfCategory": "low",
        "currentGen": false,
        "zones": [
          "eu-central-1b",
          "eu-central-1a"
        ]
      },
      "sumNodes": 3,
      "vmClass": "regular"
    },
    {
      "vm": {
        "Category": "Compute optimized",
        "type": "ecs.sn1.medium",
        "avgPrice": 0,
        "onDemandPrice": 0.132,
        "cpusPerVm": 2,
        "memPerVm": 4,
        "gpusPerVm": 0,
        "burst": false,
        "networkPerf": "0.5 Gbit/s",
        "networkPerfCategory": "low",
        "currentGen": false,
        "zones": [
          "eu-central-1a"
        ]
      },
      "sumNodes": 0,
      "vmClass": "spot"
    },
    {
      "vm": {
        "Category": "General purpose",
        "type": "ecs.sn2.medium",
        "avgPrice": 0,
        "onDemandPrice": 0.17600000000000002,
        "cpusPerVm": 2,
        "memPerVm": 8,
        "gpusPerVm": 0,
        "burst": false,
        "networkPerf": "0.5 Gbit/s",
        "networkPerfCategory": "low",
        "currentGen": false,
        "zones": [
          "eu-central-1a"
        ]
      },
      "sumNodes": 0,
      "vmClass": "spot"
    },
    {
      "vm": {
        "Category": "General purpose",
        "type": "ecs.n4.large",
        "avgPrice": 0,
        "onDemandPrice": 0.10400000000000001,
        "cpusPerVm": 2,
        "memPerVm": 4,
        "gpusPerVm": 0,
        "burst": false,
        "networkPerf": "0.5 Gbit/s",
        "networkPerfCategory": "low",
        "currentGen": false,
        "zones": [
          "eu-central-1a"
        ]
      },
      "sumNodes": 0,
      "vmClass": "spot"
    }
  ],
  "accuracy": {
    "memory": 12,
    "cpu": 6,
    "nodes": 3,
    "zone": [
      "eu-central-1a"
    ],
    "regularPrice": 0.15000000000000002,
    "regularNodes": 3,
    "spotPrice": 0,
    "spotNodes": 0,
    "totalPrice": 0.15000000000000002
  }
}

The minNodes number is 4 in the request, and Recommender returns with 3 nodes.