61 lines
1.9 KiB
Rust
61 lines
1.9 KiB
Rust
/*
|
|
* File: unbounded_knapsack.rs
|
|
* Created Time: 2023-07-09
|
|
* Author: codingonion (coderonion@gmail.com)
|
|
*/
|
|
|
|
/* Complete knapsack: Dynamic programming */
|
|
fn unbounded_knapsack_dp(wgt: &[i32], val: &[i32], cap: usize) -> i32 {
|
|
let n = wgt.len();
|
|
// Initialize dp table
|
|
let mut dp = vec![vec![0; cap + 1]; n + 1];
|
|
// State transition
|
|
for i in 1..=n {
|
|
for c in 1..=cap {
|
|
if wgt[i - 1] > c as i32 {
|
|
// If exceeding the knapsack capacity, do not choose item i
|
|
dp[i][c] = dp[i - 1][c];
|
|
} else {
|
|
// The greater value between not choosing and choosing item i
|
|
dp[i][c] = std::cmp::max(dp[i - 1][c], dp[i][c - wgt[i - 1] as usize] + val[i - 1]);
|
|
}
|
|
}
|
|
}
|
|
return dp[n][cap];
|
|
}
|
|
|
|
/* Complete knapsack: Space-optimized dynamic programming */
|
|
fn unbounded_knapsack_dp_comp(wgt: &[i32], val: &[i32], cap: usize) -> i32 {
|
|
let n = wgt.len();
|
|
// Initialize dp table
|
|
let mut dp = vec![0; cap + 1];
|
|
// State transition
|
|
for i in 1..=n {
|
|
for c in 1..=cap {
|
|
if wgt[i - 1] > c as i32 {
|
|
// If exceeding the knapsack capacity, do not choose item i
|
|
dp[c] = dp[c];
|
|
} else {
|
|
// The greater value between not choosing and choosing item i
|
|
dp[c] = std::cmp::max(dp[c], dp[c - wgt[i - 1] as usize] + val[i - 1]);
|
|
}
|
|
}
|
|
}
|
|
dp[cap]
|
|
}
|
|
|
|
/* Driver Code */
|
|
pub fn main() {
|
|
let wgt = [1, 2, 3];
|
|
let val = [5, 11, 15];
|
|
let cap: usize = 4;
|
|
|
|
// Dynamic programming
|
|
let res = unbounded_knapsack_dp(&wgt, &val, cap);
|
|
println!("The maximum item value without exceeding knapsack capacity is {res}");
|
|
|
|
// Space-optimized dynamic programming
|
|
let res = unbounded_knapsack_dp_comp(&wgt, &val, cap);
|
|
println!("The maximum item value without exceeding knapsack capacity is {res}");
|
|
}
|