828 pass

2699-231124/main.cpp

@@ -1,3 +1,4 @@
+//https://leetcode.com/problems/modify-graph-edge-weights/
 #include<bits/stdc++.h>
 using namespace std;
 class Solution{
@@ -6,7 +7,9 @@ public:
 
     }
 
-}
+};
+
 int main(){
+    int n;
 
 }

828-231125-pass/main.cpp

@@ -0,0 +1,89 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+class Solution{
+public:
+    int uniqueLetterString(string s){
+        const int constraint_length = s.size() + 10;
+        const int ch_nums = 26;
+        const int first_char = (int)'A';
+        
+        // store the distance, first is the distance to the previous charactor, second is the distance to the next char
+        pair<int,int> ch_dist[constraint_length];
+        //index store index from 1
+        int index[ch_nums] = {};
+
+        // try to find the distance
+        for(int i = 0 ; i < s.size() ; i++){
+            const int word_th = s[i] - first_char;
+            ch_dist[i + 1].first = i + 1 - index[word_th];             
+            if(index[word_th] != 0)
+                ch_dist[index[word_th]].second = i + 1 - index[word_th];
+            index[word_th] = i + 1;
+       }
+
+        for(int i = 0 ; i < ch_nums ; i++){
+            if(index[i]!=0){
+                ch_dist[index[i]].second = s.size() + 1 - index[i];
+                // cout<<i<<' '<<s.size()<<'+'<<1<<'-'<<index[i]<<'='<<s.size() + 1 - index[i]<<endl;
+            }
+        }
+
+        for(int i = 1 ; i < s.size() + 1 ; i++){
+            // cout<< i<<' '<< ch_dist[i].first<< ' '<< ch_dist[i].second<<' '<<index[s[i-1]-'A']<<endl;
+        }
+
+        long long rlt = 0;
+
+        for(int i = 1 ; i < s.size() + 1 ; i++){
+            rlt += ch_dist[i].first + ch_dist[i].second - 1;
+
+            int pre, nxt;
+
+            // if(i == ch_dist[i].first){
+            //     pre = i - 1;
+            // }
+            // else{
+            //     pre = i - ch_dist[i].first ;
+            // }
+
+            // if(i == index[s[i - 1]-'A'])
+            //     nxt = s.size() - i;
+            // else
+            //     nxt = ch_dist[i].second ;
+            pre = ch_dist[i].first - 1;
+            nxt = ch_dist[i].second - 1;
+            rlt += pre * nxt;
+            
+            // cout<<pre<<' '<<nxt<<endl;
+            
+        }
+        return rlt ;
+
+    }
+};
+
+
+
+int main(){
+    Solution sol;
+    string ex1 = "ABC";
+    cout<<ex1<<endl;
+    cout<<sol.uniqueLetterString(ex1)<<endl;
+    string ex2 = "ABA";
+    cout<<ex2<<endl;
+    cout<<sol.uniqueLetterString(ex2)<<endl;
+    string ex3 = "LEETCODE";
+    cout<<ex3<<endl;
+    cout<<sol.uniqueLetterString(ex3)<<endl;
+    string ex4 = "ABCD";
+    cout<<ex4<<endl;
+    cout<<sol.uniqueLetterString(ex4)<<endl;
+    string ex5 = "ABAC";
+    cout<<ex5<<endl;
+    cout<<sol.uniqueLetterString(ex5)<<endl;
+    string ex6 = "ABACA";
+    cout<<ex6<<endl;
+    cout<<sol.uniqueLetterString(ex6)<<endl;
+    return 0;
+}