原创，背包问题的四种解法，回溯法，动态规划法，以及两种蛮力法，C++代码，编译运行通过，结果正确，可以比较各种方法的效率。-The original, four solutions of the knapsack problem, backtracking, dynamic programming, and two brute force method, C++ code, compile, run through, the result is correct, you can compare