It looks like cucumber...Is it wild cucumber? I have been searching for its name quite some time, finally got it: Coccinia grandis. another name is ivy gourd, also known as baby watermelon, little gourd or gentleman's toes, it is a tropical vine. Fruits are edible.
Photos taken in Punngol end, along the walking path of the park connector network, there are a few vines there growing very well.