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Merge pull request #51 from shoaibrayeen/patch-2

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Change Iterative Function - Merge Print and Iterative function
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huihut 2019-09-12 11:38:23 +08:00 committed by GitHub
commit 797aab3d4e
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1 changed files with 29 additions and 24 deletions
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53
Problems/KnapsackProblem/pack.cpp
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@ -2,21 +2,16 @@
#include <algorithm>
using namespace std;
int *w = NULL; // 存储每件物品重量的数组指针
int *v = NULL; // 存储每件物品价值的数组指针
int **T = NULL; // 存储背包问题表格的数组指针
int n; // 物品个数n
int W; // 背包总承重W
// 返回两个值的最大值
int max(int a, int b)
{
int max(int a, int b) {
return (a > b) ? a : b;
}
// 迭代法，能显示背包问题的表格
void packIterative()
{
int packIterative(int n, int W, int *w, int *v) {
// 循环遍历n行
for (int i = 1; i <= n; ++i)
{
@ -32,22 +27,23 @@ void packIterative()
T[i][j] = T[i - 1][j];
}
}
return T[n][W];
}
// 递归法，不支持显示背包问题的表格
int packRecursive(int i, int j, int *w, int *v)
{
int packRecursive(int n, int W, int *w, int *v) {
// 结束条件（初始条件），i或者j为0时最大总价值为0
if (i == 0 || j == 0)
if (n == 0 || W == 0) {
return 0;
}
// 第i个物品不能装下，则递归装i-1个
if (w[i] > j)
return packRecursive(i - 1, j, w, v);
if (w[n] > W) {
return packRecursive(n - 1, W, w, v);
}
//第i个物品能装下，则比较包括第i个物品和不包括第i个物品，取其最大值
else
return max(v[i] + packRecursive(i - 1, j - w[i], w, v), packRecursive(i - 1, j, w, v));
else {
return max(v[n] + packRecursive(n - 1, W - w[n], w, v), packRecursive(n - 1, W, w, v));
}
}
// 打印背包问题的表格
@ -70,8 +66,11 @@ void printT(int n, int W)
}
}
int main()
{
int main() {
int *w = NULL; // 存储每件物品重量的数组指针
int *v = NULL; // 存储每件物品价值的数组指针
int n; // 物品个数n
int W; // 背包总承重W
cout << "---------------- 背包问题 ----------------" << endl;
cout << "请输入物品数 n (n>=0) " << endl;
@ -100,8 +99,8 @@ int main()
// 分配空间
// 对w和v分配n+1大小
w = new int[n+1];
v = new int[n+1];
w = new int[n + 1];
v = new int[n + 1];
// 对T分配n+1行，并初始化为0
T = new int *[n + 1]();
@ -114,7 +113,7 @@ int main()
// 输入背包的重量和价值
for (auto i = 1; i <= n; i++)
{
cout << "请输入第 " << i << " 个背包的重量和价值（用空格隔开）" << endl;
cout << "请输入第 " << i << " 个物品的重量和价值（用空格隔开）" << endl;
cin >> w[i] >> v[i];
if (cin.fail() || w[i] < 0 || v[i] < 0)
{
@ -139,8 +138,7 @@ int main()
case 1:
{
// 迭代法，能显示背包问题的表格
packIterative();
cout << "能装下物品的最大价值为 " << T[n][W] << endl;
cout << "能装下物品的最大价值为 " << packIterative(n, W, w, v) << endl;
cout << "------------------------------------------------" << endl;
printT(n, W);
break;
@ -160,6 +158,13 @@ int main()
cout << "------------------------------------------------" << endl;
delete w;
delete v;
for (int i = 0; i <= n; ++i) {
delete[] T[i];
}
delete[] T;
system("pause");
return 0;
}