hello-algo/codes/rust/chapter_backtracking/subset_sum_i_naive.rs

48 lines
1.5 KiB
Rust
Raw Normal View History

/*
* File: subset_sum_i_naive.rs
* Created Time: 2023-07-09
* Author: codingonion (coderonion@gmail.com)
*/
/* 回溯算法:子集和 I */
fn backtrack(mut state: Vec<i32>, target: i32, total: i32, choices: &[i32], res: &mut Vec<Vec<i32>>) {
// 子集和等于 target 时,记录解
if total == target {
res.push(state);
return;
}
// 遍历所有选择
for i in 0..choices.len() {
// 剪枝:若子集和超过 target ,则跳过该选择
if total + choices[i] > target {
continue;
}
// 尝试:做出选择,更新元素和 total
state.push(choices[i]);
// 进行下一轮选择
backtrack(state.clone(), target, total + choices[i], choices, res);
// 回退:撤销选择,恢复到之前的状态
state.pop();
}
}
/* 求解子集和 I包含重复子集 */
fn subset_sum_i_naive(nums: &[i32], target: i32) -> Vec<Vec<i32>> {
let state = Vec::new(); // 状态(子集)
let total = 0; // 子集和
let mut res = Vec::new(); // 结果列表(子集列表)
backtrack(state, target, total, nums, &mut res);
res
}
/* Driver Code */
pub fn main() {
let nums = [ 3, 4, 5 ];
let target = 9;
let res = subset_sum_i_naive(&nums, target);
println!("输入数组 nums = {:?}, target = {}", &nums, target);
println!("所有和等于 {} 的子集 res = {:?}", target, &res);
println!("请注意,该方法输出的结果包含重复集合");
}