mirror of
https://github.com/krahets/hello-algo.git
synced 2024-12-24 11:06:29 +08:00
7359a7cb4b
* feat(swift): review for chapter_computational_complexity * feat(swift): review for chapter_data_structure * feat(swift): review for chapter_array_and_linkedlist * feat(swift): review for chapter_stack_and_queue * feat(swift): review for chapter_hashing * feat(swift): review for chapter_tree * feat(swift): add codes for heap article * feat(swift): review for chapter_heap * feat(swift): review for chapter_graph * feat(swift): review for chapter_searching * feat(swift): review for chapter_sorting * feat(swift): review for chapter_divide_and_conquer * feat(swift): review for chapter_backtracking * feat(swift): review for chapter_dynamic_programming * feat(swift): review for chapter_greedy * feat(swift): review for utils * feat(swift): update ci tool * feat(swift): trailing closure * feat(swift): array init * feat(swift): map index
63 lines
1.9 KiB
Swift
63 lines
1.9 KiB
Swift
/**
|
||
* File: unbounded_knapsack.swift
|
||
* Created Time: 2023-07-15
|
||
* Author: nuomi1 (nuomi1@qq.com)
|
||
*/
|
||
|
||
/* 完全背包:动态规划 */
|
||
func unboundedKnapsackDP(wgt: [Int], val: [Int], cap: Int) -> Int {
|
||
let n = wgt.count
|
||
// 初始化 dp 表
|
||
var dp = Array(repeating: Array(repeating: 0, count: cap + 1), count: n + 1)
|
||
// 状态转移
|
||
for i in 1 ... n {
|
||
for c in 1 ... cap {
|
||
if wgt[i - 1] > c {
|
||
// 若超过背包容量,则不选物品 i
|
||
dp[i][c] = dp[i - 1][c]
|
||
} else {
|
||
// 不选和选物品 i 这两种方案的较大值
|
||
dp[i][c] = max(dp[i - 1][c], dp[i][c - wgt[i - 1]] + val[i - 1])
|
||
}
|
||
}
|
||
}
|
||
return dp[n][cap]
|
||
}
|
||
|
||
/* 完全背包:空间优化后的动态规划 */
|
||
func unboundedKnapsackDPComp(wgt: [Int], val: [Int], cap: Int) -> Int {
|
||
let n = wgt.count
|
||
// 初始化 dp 表
|
||
var dp = Array(repeating: 0, count: cap + 1)
|
||
// 状态转移
|
||
for i in 1 ... n {
|
||
for c in 1 ... cap {
|
||
if wgt[i - 1] > c {
|
||
// 若超过背包容量,则不选物品 i
|
||
dp[c] = dp[c]
|
||
} else {
|
||
// 不选和选物品 i 这两种方案的较大值
|
||
dp[c] = max(dp[c], dp[c - wgt[i - 1]] + val[i - 1])
|
||
}
|
||
}
|
||
}
|
||
return dp[cap]
|
||
}
|
||
|
||
@main
|
||
enum UnboundedKnapsack {
|
||
/* Driver Code */
|
||
static func main() {
|
||
let wgt = [1, 2, 3]
|
||
let val = [5, 11, 15]
|
||
let cap = 4
|
||
|
||
// 动态规划
|
||
var res = unboundedKnapsackDP(wgt: wgt, val: val, cap: cap)
|
||
print("不超过背包容量的最大物品价值为 \(res)")
|
||
|
||
// 空间优化后的动态规划
|
||
res = unboundedKnapsackDPComp(wgt: wgt, val: val, cap: cap)
|
||
print("不超过背包容量的最大物品价值为 \(res)")
|
||
}
|
||
}
|