代码随想录一刷day27

提示：文章写完后，目录可以自动生成，如何生成可参考右边的帮助文档

---

一、力扣39. 组合总和

class Solution {
    private List<Integer> path = new ArrayList<>();
    private List<List<Integer>> result = new ArrayList<>();
    private int count = 0;
    public List<List<Integer>> combinationSum(int[] candidates, int target) {
        Arrays.sort(candidates);
        fun(candidates, target, 0);
        return result;
    }
    public void fun(int[] candidates, int target, int startIndex){
        if(count == target){
            result.add(new ArrayList<>(path));
            return;
        }
        for(int i = startIndex; i< candidates.length; i++){
            if(count + candidates[i] > target){
                return;
            }
            path.add(candidates[i]);
            count += candidates[i];
            fun(candidates, target, i);
            path.remove(path.size()-1);
            count -= candidates[i];
        }
    }
}

二、力扣40. 组合总和 II

class Solution {
    private List<Integer> path = new ArrayList<>();
    private List<List<Integer>> res = new ArrayList<>();
    private boolean[] flag;
    private int count = 0;
    public List<List<Integer>> combinationSum2(int[] candidates, int target) {
        flag = new boolean[candidates.length];
        Arrays.fill(flag, false);
        Arrays.sort(candidates);
        fun(candidates, target, 0);
        return res;
    }
    public void fun(int[] candidates, int target, int startIndex){
        if(count == target){
            res.add(new ArrayList<>(path));
            return ;
        }
        for(int i = startIndex; i < candidates.length; i++){
            if(count + candidates[i] > target){
                break;
            }
            if(i>0 && candidates[i] == candidates[i-1] && !flag[i-1]){
                continue;
            }
            flag[i] = true;
            path.add(candidates[i]);
            count += candidates[i];
            fun(candidates, target, i+1);
            flag[i] = false;
            path.remove(path.size()-1);
            count -= candidates[i];
        }
    }
}

三、力扣131.分割回文串

class Solution {
    private List<String> path = new ArrayList<>();
    private List<List<String>> res = new ArrayList<>();
    public List<List<String>> partition(String s) {
        fun(s, 0);
        return res;
    }
    private void fun(String s, int startIndex){
        if(startIndex >= s.length()){
            res.add(new ArrayList<>(path));
            return ;
        }
        for(int i = startIndex; i< s.length(); i++){
            if(isfun(s, startIndex, i)){
                path.add(s.substring(startIndex, i+1));
            }else{
                continue;
            }
            fun(s, i+1);
            path.remove(path.size()-1);
        }
    }
    private boolean isfun(String s, int begin, int end){
        for(int i = begin, j = end; i <= j; i ++, j --){
            if(s.charAt(i) != s.charAt(j)){
                return false;
            }
        }
        return true;
    }
}