Slice beans diagonally into 1 1/2-inch lengths. Cut chicken into 1-inch cubes. Place a 10- to 12-inch frying pan over high heat. When pan is hot, add oil and beans; stir-fry 2 minutes.
Add chicken and cook, stirring occasionally, until lightly browned, about 4 minutes. Add curry paste, coconut milk, and sugar. Reduce heat to low and stir until curry paste is well blended. Add bamboo shoots; continue cooking until hot, 3 to 4 minutes. Add fish sauce to taste.