As a fundamental issue in Wireless Sensor Networks, deployment is a research topic that has attracted much attention in recent years. Indeed, the number and locations of sensors deployed in a region of interest determine the topology of the network, which will further influence many of its intrinsic properties, such as its coverage, connectivity, cost, and lifetime. In this paper, we propose a polynomial-time deployment algorithm called Simulated Annealing-based sensor Deployment Algorithm (SADA). SADA is able to determine the minimum number of sensors and their locations to meet the desired user detection requirements.