Why did Wang Can's Poem of Joy win in Qiting Gambling?

The story of "painting a wall and hanging a flag pavilion" (this story is also called "gambling songs and hanging a flag pavilion"). See Tang Xue's "Rare Collection and Different Records", and the summary is as follows: In Kaiyuan, poets Wang Changling, Gao Shi and Wang Zhihuan were equally famous. One day, three poets were holding banners and drinking wine. There are four generations of excellent prostitutes in Russia. Changling and others met privately and said, "My generation is good at poetry. If we don't decide our own names, we can watch closely what Zhu Ling is doing. It would be better if there were many poems in the lyrics. " Suddenly, a singer sang: "Cold rain at night, Wu ..." Changling said: "A quatrain." He found another joke and said, "Open your eyes and cry ..." When appropriate, he quoted a hand-painted wall and said, "A quatrain." Looking for another singer, he said, "Give me a broom to open the golden palace ..." Changling pulled out his other hand and said, "Two quatrains." Huan has long been famous in the world, because she refers to the daughter and says, "If this son is not singing my poem, I will never dare to argue with him all my life." Tuo is my poem. You should worship under the bed and take me as your teacher. "Because of laughter. After a while, when the voice sounded, he said, "The Yellow River is far above the white clouds ..." Because of the loud laughter. Whether this story is true or not, it is to highlight Wang Zhihuan. Of the three poets in the story, Wang Zhihuan is undoubtedly the most important, and the content of the story is obviously beneficial to him and his poems. Prostitutes have sung, no matter how many, only the best singer is the best. In fact, the best is equal to the most discerning. Many singers are not good. Those people are just mediocre people, and the best one sings the best poems. In addition, there are only six quatrains handed down from generation to generation by Wang Zhihuan, but as long as future generations like poetry, almost no one does not know his poem name. "Three hundred Tang Poems" selected two of his poems, one is "Lusu" and the other is "Liangzhou Ci". Three hundred Tang Poems is the most famous collection of poems in China, and it is worth noting that one third of the works have been selected. These two poems are also the best among the 300 Tang poems, so they are also the best poems in the history of China literature. They are copied as follows: the mountains cover the white sun, and the oceans deplete the golden rivers. A hundred feet of pole head, go further-In the Heron Tower, the Yellow River is far above the white clouds, and Wan Ren is a lonely city. Why use the elegy of willow to complain about the delay of spring, old Yumenguan, a spring breeze is not blowing! -"Liangzhou Ci"