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.
47 lines
1.3 KiB
47 lines
1.3 KiB
/*
|
|
* File: permutations_i.rs
|
|
* Created Time: 2023-07-15
|
|
* Author: codingonion (coderonion@gmail.com)
|
|
*/
|
|
|
|
/* 回溯演算法：全排列 I */
|
|
fn backtrack(mut state: Vec<i32>, choices: &[i32], selected: &mut [bool], res: &mut Vec<Vec<i32>>) {
|
|
// 當狀態長度等於元素數量時，記錄解
|
|
if state.len() == choices.len() {
|
|
res.push(state);
|
|
return;
|
|
}
|
|
// 走訪所有選擇
|
|
for i in 0..choices.len() {
|
|
let choice = choices[i];
|
|
// 剪枝：不允許重複選擇元素
|
|
if !selected[i] {
|
|
// 嘗試：做出選擇，更新狀態
|
|
selected[i] = true;
|
|
state.push(choice);
|
|
// 進行下一輪選擇
|
|
backtrack(state.clone(), choices, selected, res);
|
|
// 回退：撤銷選擇，恢復到之前的狀態
|
|
selected[i] = false;
|
|
state.pop();
|
|
}
|
|
}
|
|
}
|
|
|
|
/* 全排列 I */
|
|
fn permutations_i(nums: &mut [i32]) -> Vec<Vec<i32>> {
|
|
let mut res = Vec::new(); // 狀態（子集）
|
|
backtrack(Vec::new(), nums, &mut vec![false; nums.len()], &mut res);
|
|
res
|
|
}
|
|
|
|
/* Driver Code */
|
|
pub fn main() {
|
|
let mut nums = [1, 2, 3];
|
|
|
|
let res = permutations_i(&mut nums);
|
|
|
|
println!("輸入陣列 nums = {:?}", &nums);
|
|
println!("所有排列 res = {:?}", &res);
|
|
}
|