EVM中循环的成本是多少

代码如下,我好像已经看到GAS爆炸的一幕了?

//按dna大小排列的链表
    mapping(uint256 => uint256) private mNextStudents;
    //链表的头
    uint256 private constant GUARD = 10000;

    constructor() public {
        mNextStudents[GUARD] = GUARD;
    }

    //prevTokenid.dna大于等于_newDna且_newDna>_nextTokenid.dna
    function _verifyIndex(
        uint256 _prevTokenid,
        uint256 _newDna,
        uint256 _nextTokenid
    ) private view returns (bool) {
        return
            (_prevTokenid == GUARD || mTigers[_prevTokenid].dna >= _newDna) &&
            (_nextTokenid == GUARD || _newDna > mTigers[_nextTokenid].dna);
    }

    //遍历寻找当前插入位置
    function _findIndex(uint256 _newDna) private view returns (uint256) {
        uint256 tokenid = GUARD;
        while (true) {
            if (_verifyIndex(tokenid, _newDna, mNextStudents[tokenid])) {
                return tokenid;
            }
            tokenid = mNextStudents[tokenid];
        }
    }

    //添加NFT链表
    function _addTiger(uint256 _tokenid) private {
        uint256 tokenid = _findIndex(mTigers[_tokenid].dna);
        //指向tokenid原先指向的id
        mNextStudents[_tokenid] = mNextStudents[tokenid];
        //tokenid指向当前ID
        mNextStudents[tokenid] = _tokenid;
    }

    //获取排名
    function _getTop(uint256 _top)
        internal
        view
        virtual
        returns (uint256[] memory _res)
    {
        _res = new uint256[](_top);
        uint256 tokenid = mNextStudents[GUARD];
        for (uint256 i = 0; i < _top; i++) {
            if (tokenid != GUARD) {
                _res[i] = tokenid;
                tokenid = mNextStudents[tokenid];
            } else {
                _res[i] = 999;
            }
        }
    }