代码随想录算法训练营第二十九天|* 491.递增子序列* 46.全排列* 47.全排列 II-优快云博客

本文链接：https://blog.youkuaiyun.com/minodeer/article/details/137384693

博客围绕LeetCode算法题展开，涉及深度优先算法，具体题目有491.递增子序列、46.全排列、47.全排列II，为信息技术领域算法学习提供参考。

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* 491.递增子序列

class Solution {
public:
    vector<vector<int>> b;
    vector<int> a;
    void dfs(vector<int>& nums, int s) {
        if (a.size() > 1)
            b.push_back(a);
        unordered_set<int> mark;
        for (int i = s; i < nums.size(); i++) {
            if ((!a.empty() && nums[i] < a.back()) ||
                mark.find(nums[i]) != mark.end()) {
                    continue;
                }
                mark.insert(nums[i]);
                a.push_back(nums[i]);
                dfs(nums, i + 1);
                a.pop_back();
            
        }
    }
    vector<vector<int>> findSubsequences(vector<int>& nums) {
        dfs(nums, 0);
        return b;
    }
};

* 46.全排列

class Solution {
public:
    vector<int> a;
    vector<vector<int>> b;
    void dfs(vector<int>& nums,int step,vector<bool>& mark) {
        if (step == nums.size()) {
            b.push_back(a);
            return;
        }
        for (int i = 0; i < nums.size(); i++) {
            if(mark[i]==0){
            mark[i]=1;
            a.push_back(nums[i]);
            dfs(nums,step+1,mark);
            mark[i]=0;
            a.pop_back();}
        }
    }
    vector<vector<int>> permute(vector<int>& nums) {
        vector<bool>mark(nums.size(),0);
        dfs(nums,0,mark);
        return b;
    }
};

* 47.全排列 II

class Solution {
public:
    vector<int> a;
    vector<vector<int>> b;
    void dfs(vector<int>& nums, vector<bool>& mark) {
        if (a.size() == nums.size()) {
            b.push_back(a);
            return;
        }
        for (int i = 0; i < nums.size(); i++) {
            if (i>0 && nums[i] == nums[i - 1] && mark[i - 1] == 1)
                continue;
            if (mark[i] == 0) {
                mark[i] = 1;
                a.push_back(nums[i]);
                dfs(nums, mark);
                mark[i] = 0;
                a.pop_back();
            }
        }
    }
    vector<vector<int>> permuteUnique(vector<int>& nums) {
        sort(nums.begin(), nums.end());
        vector<bool> mark(nums.size(), 0);
        dfs(nums, mark);
        return b;
    }
};