1

Author: Ainevsia

notes/src/SUMMARY.md

@@ -88,3 +88,5 @@
 - [day 25](./day25.md)
   - [216. 组合总和 III](./day25/lc216.md)
   - [17. 电话号码的字母组合](./day25/lc17.md)
+- [day 27](./day27.md)
+- [remains](./remains.md)

notes/src/day27.md

@@ -0,0 +1,88 @@
+# 39. 组合总和
+
+```cpp
+class Solution {
+public:
+    vector<vector<int>>res;
+    vector<int>cur;vector<int>candidates;
+    int s=0,t;
+    void bt(int start){
+        if(s>=t){if(s==t)res.push_back(cur);return;}
+        for(int j=start;j<candidates.size();j++){int i=candidates[j];
+            cur.push_back(i);s+=i;
+            bt(j);
+            cur.pop_back();s-=i;
+        }
+    }
+    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
+        t=target;this->candidates=candidates;bt(0);return res;
+    }
+};
+```
+
+# 40.组合总和II
+
+```cpp
+class Solution {
+public:
+    vector<vector<int>>res;
+    vector<int>cur;vector<int>candidates;
+    int s=0,t;
+    void bt(int start){
+        if(s>=t){if(s==t)res.push_back(cur);return;}
+        for(int j=start;j<candidates.size();j++){
+            int i=candidates[j];
+            
+            if(j>start&&candidates[j]==candidates[j-1])continue;
+            cur.push_back(i);s+=i;
+            bt(j+1);
+            cur.pop_back();s-=i;
+        }
+    }
+    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
+        t=target;sort(candidates.begin(),candidates.end());this->candidates=candidates;bt(0);return res;
+    }
+};
+```
+
+`if(j>start&&candidates[j]==candidates[j-1])continue;`这而想了很久，一直以为是j大于0
+
+为了结果不重复，所以剪枝是必须要进行的操作
+
+# 131.分割回文串
+
+```cpp
+class Solution {
+public:
+    string s;vector<vector<string>>res;vector<string>cur;
+    bool valid(int l,int r){
+        int lptr=l,rptr=r;while(lptr<=r){if(s[lptr]!=s[rptr])return false;lptr++;rptr--;}return true;
+    }
+    void bt(int start){
+        if(start==s.size()){res.push_back(cur);return;}
+        for(int i=start;i<s.size();i++){
+            if(valid(start,i)){
+                cur.push_back(s.substr(start,i-start+1));
+                bt(i+1);
+                cur.pop_back();
+            }
+        }
+    }
+    vector<vector<string>> partition(string s) {
+        this->s=s;bt(0);return res;
+    }
+};
+```
+
+# 93.复原IP地址
+
+https://programmercarl.com/0093.%E5%A4%8D%E5%8E%9FIP%E5%9C%B0%E5%9D%80.html#%E7%AE%97%E6%B3%95%E5%85%AC%E5%BC%80%E8%AF%BE
+
+```cpp
+class Solution {
+public:
+    vector<string> restoreIpAddresses(string s) {
+
+    }
+};
+```