Algorithm
▪Greed – A greedy algorithm is any algorithm that follows the problem solving heuristic of making the locally optimal choice at each stage with the intent of finding a global optimum – Efficient, but may not be the global optimum 处理减缩问题 这个算法出来的不是最优解，但总能出来一个解 ▪ Brute-force – Enumerate all possible combinations – Global optimum but inefficient 列举所有可能性 ▪ Backtracking – It ensures that only solutions that are possible are generated. -确保只产生可能的解决方案。如果进入死胡同，就会回到上一步再继续前进，迷宫？