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krahets
2023-05-16 14:51:37 +08:00
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chapter_backtracking/permutations_problem.md
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@@ -140,25 +140,111 @@ comments: true
=== "Go"
```go title="permutations_i.go"
[class]{}-[func]{backtrack}
/* 回溯算法：全排列 I */
func backtrackI(state *[]int, choices *[]int, selected *[]bool, res *[][]int) {
// 当状态长度等于元素数量时，记录解
if len(*state) == len(*choices) {
newState := append([]int{}, *state...)
*res = append(*res, newState)
}
// 遍历所有选择
for i := 0; i < len(*choices); i++ {
choice := (*choices)[i]
// 剪枝：不允许重复选择元素 且 不允许重复选择相等元素
if !(*selected)[i] {
// 尝试：做出选择，更新状态
(*selected)[i] = true
*state = append(*state, choice)
// 进行下一轮选择
backtrackI(state, choices, selected, res)
// 回退：撤销选择，恢复到之前的状态
(*selected)[i] = false
*state = (*state)[:len(*state)-1]
}
}
}
[class]{}-[func]{permutationsI}
/* 全排列 I */
func permutationsI(nums []int) [][]int {
res := make([][]int, 0)
state := make([]int, 0)
selected := make([]bool, len(nums))
backtrackI(&state, &nums, &selected, &res)
return res
}
```
=== "JavaScript"
```javascript title="permutations_i.js"
[class]{}-[func]{backtrack}
/* 回溯算法：全排列 I */
function backtrack(state, choices, selected, res) {
// 当状态长度等于元素数量时，记录解
if (state.length === choices.length) {
res.push([...state]);
return;
}
// 遍历所有选择
choices.forEach((choice, i) => {
// 剪枝：不允许重复选择元素 且 不允许重复选择相等元素
if (!selected[i]) {
// 尝试：做出选择，更新状态
selected[i] = true;
state.push(choice);
// 进行下一轮选择
backtrack(state, choices, selected, res);
// 回退：撤销选择，恢复到之前的状态
selected[i] = false;
state.pop();
}
});
}
[class]{}-[func]{permutationsI}
/* 全排列 I */
function permutationsI(nums) {
const res = [];
backtrack([], nums, Array(nums.length).fill(false), res);
return res;
}
```
=== "TypeScript"
```typescript title="permutations_i.ts"
[class]{}-[func]{backtrack}
/* 回溯算法：全排列 I */
function backtrack(
state: number[],
choices: number[],
selected: boolean[],
res: number[][]
): void {
// 当状态长度等于元素数量时，记录解
if (state.length === choices.length) {
res.push([...state]);
return;
}
// 遍历所有选择
choices.forEach((choice, i) => {
// 剪枝：不允许重复选择元素 且 不允许重复选择相等元素
if (!selected[i]) {
// 尝试：做出选择，更新状态
selected[i] = true;
state.push(choice);
// 进行下一轮选择
backtrack(state, choices, selected, res);
// 回退：撤销选择，恢复到之前的状态
selected[i] = false;
state.pop();
}
});
}
[class]{}-[func]{permutationsI}
/* 全排列 I */
function permutationsI(nums: number[]): number[][] {
const res: number[][] = [];
backtrack([], nums, Array(nums.length).fill(false), res);
return res;
}
```
=== "C"
@@ -388,25 +474,118 @@ comments: true
=== "Go"
```go title="permutations_ii.go"
[class]{}-[func]{backtrack}
/* 回溯算法：全排列 II */
func backtrackII(state *[]int, choices *[]int, selected *[]bool, res *[][]int) {
// 当状态长度等于元素数量时，记录解
if len(*state) == len(*choices) {
newState := append([]int{}, *state...)
*res = append(*res, newState)
}
// 遍历所有选择
duplicated := make(map[int]struct{}, 0)
for i := 0; i < len(*choices); i++ {
choice := (*choices)[i]
// 剪枝：不允许重复选择元素 且 不允许重复选择相等元素
if _, ok := duplicated[choice]; !ok && !(*selected)[i] {
// 尝试：做出选择，更新状态
// 记录选择过的元素值
duplicated[choice] = struct{}{}
(*selected)[i] = true
*state = append(*state, choice)
// 进行下一轮选择
backtrackI(state, choices, selected, res)
// 回退：撤销选择，恢复到之前的状态
(*selected)[i] = false
*state = (*state)[:len(*state)-1]
}
}
}
[class]{}-[func]{permutationsII}
/* 全排列 II */
func permutationsII(nums []int) [][]int {
res := make([][]int, 0)
state := make([]int, 0)
selected := make([]bool, len(nums))
backtrackII(&state, &nums, &selected, &res)
return res
}
```
=== "JavaScript"
```javascript title="permutations_ii.js"
[class]{}-[func]{backtrack}
/* 回溯算法：全排列 II */
function backtrack(state, choices, selected, res) {
// 当状态长度等于元素数量时，记录解
if (state.length === choices.length) {
res.push([...state]);
return;
}
// 遍历所有选择
const duplicated = new Set();
choices.forEach((choice, i) => {
// 剪枝：不允许重复选择元素 且 不允许重复选择相等元素
if (!selected[i] && !duplicated.has(choice)) {
// 尝试：做出选择，更新状态
duplicated.add(choice); // 记录选择过的元素值
selected[i] = true;
state.push(choice);
// 进行下一轮选择
backtrack(state, choices, selected, res);
// 回退：撤销选择，恢复到之前的状态
selected[i] = false;
state.pop();
}
});
}
[class]{}-[func]{permutationsII}
/* 全排列 II */
function permutationsII(nums) {
const res = [];
backtrack([], nums, Array(nums.length).fill(false), res);
return res;
}
```
=== "TypeScript"
```typescript title="permutations_ii.ts"
[class]{}-[func]{backtrack}
/* 回溯算法：全排列 II */
function backtrack(
state: number[],
choices: number[],
selected: boolean[],
res: number[][]
): void {
// 当状态长度等于元素数量时，记录解
if (state.length === choices.length) {
res.push([...state]);
return;
}
// 遍历所有选择
const duplicated = new Set();
choices.forEach((choice, i) => {
// 剪枝：不允许重复选择元素 且 不允许重复选择相等元素
if (!selected[i] && !duplicated.has(choice)) {
// 尝试：做出选择，更新状态
duplicated.add(choice); // 记录选择过的元素值
selected[i] = true;
state.push(choice);
// 进行下一轮选择
backtrack(state, choices, selected, res);
// 回退：撤销选择，恢复到之前的状态
selected[i] = false;
state.pop();
}
});
}
[class]{}-[func]{permutationsII}
/* 全排列 II */
function permutationsII(nums: number[]): number[][] {
const res: number[][] = [];
backtrack([], nums, Array(nums.length).fill(false), res);
return res;
}
```
=== "C"