You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
60 lines
1.5 KiB
60 lines
1.5 KiB
/*
|
|
* File: coin_change_greedy.rs
|
|
* Created Time: 2023-07-22
|
|
* Author: night-cruise (2586447362@qq.com)
|
|
*/
|
|
|
|
/* 物品 */
|
|
struct Item {
|
|
w: i32, // 物品重量
|
|
v: i32, // 物品价值
|
|
}
|
|
|
|
impl Item {
|
|
fn new(w: i32, v: i32) -> Self {
|
|
Self { w, v }
|
|
}
|
|
}
|
|
|
|
/* 分数背包：贪心 */
|
|
fn fractional_knapsack(wgt: &[i32], val: &[i32], mut cap: i32) -> f64 {
|
|
// 创建物品列表，包含两个属性：重量、价值
|
|
let mut items = wgt
|
|
.iter()
|
|
.zip(val.iter())
|
|
.map(|(&w, &v)| Item::new(w, v))
|
|
.collect::<Vec<Item>>();
|
|
// 按照单位价值 item.v / item.w 从高到低进行排序
|
|
items.sort_by(|a, b| {
|
|
(b.v as f64 / b.w as f64)
|
|
.partial_cmp(&(a.v as f64 / a.w as f64))
|
|
.unwrap()
|
|
});
|
|
// 循环贪心选择
|
|
let mut res = 0.0;
|
|
for item in &items {
|
|
if item.w <= cap {
|
|
// 若剩余容量充足，则将当前物品整个装进背包
|
|
res += item.v as f64;
|
|
cap -= item.w;
|
|
} else {
|
|
// 若剩余容量不足，则将当前物品的一部分装进背包
|
|
res += item.v as f64 / item.w as f64 * cap as f64;
|
|
// 已无剩余容量，因此跳出循环
|
|
break;
|
|
}
|
|
}
|
|
res
|
|
}
|
|
|
|
/* Driver Code */
|
|
fn main() {
|
|
let wgt = [10, 20, 30, 40, 50];
|
|
let val = [50, 120, 150, 210, 240];
|
|
let cap = 50;
|
|
|
|
// 贪心算法
|
|
let res = fractional_knapsack(&wgt, &val, cap);
|
|
println!("不超过背包容量的最大物品价值为 {}", res);
|
|
}
|