Correct

心机

/ xīnjī / 
Strokes

Definition

thinking/scheme

Example

As a Noun

thinking; scheming

1
Yòngjìnxīnjī
用尽心机

exhaust one's abilities

2
Wǎngfèixīnjī
枉费心机

rack one's brains in vain

3
Fèijìnxīnjī
费尽心机

cudgel one's brains