Correct

乘兴

/ chéngxìng / 
Strokes

Definition

while in high spirits/feeling upbeat/on an impulse

Example

As a Verb

while one is in high spirits; when one is happy

1
Chéngxìng
乘兴
zuō
作
shī
诗

improvise a poem while in a joyful mood

2
Chéngxìng
乘兴
yínshī
吟诗

chant a poem when one is happy