使用動態規劃解決揹包問題的 C++ 程式
這是一個使用動態規劃解決 0-1 揹包問題的 C++ 程式。在 0-1 揹包問題中,給定一組物品,每種物品都具有重量和價值。我們需要確定每件物品包含在集合中的數量,以便總重量小於或等於給定的限制,並且總價值儘可能大。
演算法
Begin Input set of items each with a weight and a value Set knapsack capacity Create a function that returns maximum of two integers. Create a function which returns the maximum value that can be put in a knapsack of capacity W int knapSack(int W, int w[], int v[], int n) int i, wt; int K[n + 1][W + 1] for i = 0 to n for wt = 0 to W if (i == 0 or wt == 0) Do K[i][wt] = 0 else if (w[i - 1] <= wt) Compute: K[i][wt] = max(v[i - 1] + K[i - 1][wt - w[i - 1]], K[i -1][wt]) else K[i][wt] = K[i - 1][wt] return K[n][W] Call the function and print. End
示例程式碼
#include <iostream> using namespace std; int max(int x, int y) { return (x > y) ? x : y; } int knapSack(int W, int w[], int v[], int n) { int i, wt; int K[n + 1][W + 1]; for (i = 0; i <= n; i++) { for (wt = 0; wt <= W; wt++) { if (i == 0 || wt == 0) K[i][wt] = 0; else if (w[i - 1] <= wt) K[i][wt] = max(v[i - 1] + K[i - 1][wt - w[i - 1]], K[i - 1][wt]); else K[i][wt] = K[i - 1][wt]; } } return K[n][W]; } int main() { cout << "Enter the number of items in a Knapsack:"; int n, W; cin >> n; int v[n], w[n]; for (int i = 0; i < n; i++) { cout << "Enter value and weight for item " << i << ":"; cin >> v[i]; cin >> w[i]; } cout << "Enter the capacity of knapsack"; cin >> W; cout << knapSack(W, w, v, n); return 0; }
輸出
Enter the number of items in a Knapsack:4 Enter value and weight for item 0:10 50 Enter value and weight for item 1:20 60 Enter value and weight for item 2:30 70 Enter value and weight for item 3:40 90 Enter the capacity of knapsack100 40
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