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feat: Add Dart codes for chapter_backtracking and chapter_divide_and_conquer (#680)

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* feat: Add Dart codes for chapter_backtracking

* feat: Add Dart codes for chapter_divide_and_conquer

* Format Dart Code
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liuyuxin
2023-08-10 23:48:56 +08:00
committed by GitHub
parent e97eee0e18
commit 4325974af1
19 changed files with 731 additions and 18 deletions
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codes/dart/chapter_backtracking/permutations_i.dart Normal file
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/**
* File: permutations_i.dart
* Created Time: 2023-08-10
* Author: liuyuxin (gvenusleo@gmail.com)
*/
/* 回溯算法：全排列 I */
void backtrack(
List<int> state,
List<int> choices,
List<bool> selected,
List<List<int>> res,
) {
// 当状态长度等于元素数量时，记录解
if (state.length == choices.length) {
res.add(List.from(state));
return;
}
// 遍历所有选择
for (int i = 0; i < choices.length; i++) {
int 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.add(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.removeLast();
}
}
}
/* 全排列 I */
List<List<int>> permutationsI(List<int> nums) {
List<List<int>> res = [];
backtrack([], nums, List.filled(nums.length, false), res);
return res;
}
/* Driver Code */
void main() {
List<int> nums = [1, 2, 3];
List<List<int>> res = permutationsI(nums);
print("输入数组 nums = $nums");
print("所有排列 res = $res");
}