135 need to use prefix array and suffix array method to solve the probelm

135-231130-pass/main.cpp

@@ -0,0 +1,90 @@
+#include<stdcpp.h>
+using namespace std;
+
+class Solution{
+public:
+    int candy(vector<int>& ratings){
+        const int length = ratings.size();
+        const int size = 2e4+10;
+        vector<int>pref(length, 1);
+        vector<int>suff(length, 1);
+        for(int i = 1 ; i < length ;i++){
+            if(ratings[i] > ratings[i-1])
+                pref[i] = pref[i-1] + 1;
+        }
+        for(int i = length - 2 ; i >= 0 ; i--){
+            if(ratings[i] > ratings[i+1])
+                suff[i] = suff[i+1] + 1;
+        }
+        int sum = 0;
+        for(int i = 0 ; i < length ;i++)
+        sum+=max(pref[i],suff[i]);
+        return sum;
+    }
+    int candy1(vector<int>& ratings){
+        const int length = ratings.size();
+        const int size = 2e4+10;
+        int comparision[size] = {};
+        if(ratings[1] > ratings[0])
+            comparision[0] = 1;
+        else if (ratings[1] == ratings[0])
+            comparision[0] = 0;
+        else
+            comparision[0] = -1;
+        int rlt[size] = {};
+        for(int i = 1 ; i < length ; i++){
+            if(ratings[i] < ratings[i-1]){
+                comparision[i] = -1;
+                if(rlt[i-1] == 0) {
+                    rlt[i] = 2;
+                    // rlt[i-1] = 1;
+                }
+                else    rlt[i] = rlt[i-1] + 1;
+            }
+            else if(ratings[i] == ratings[i - 1]){
+                comparision[i] = 0;
+            }
+            else{
+                comparision[i] = 1;
+            }
+        }
+        for(int i = 1 ; i < length ; i++){
+            if(rlt[i] == 0){
+                if(comparision[i] == 0)
+                    rlt[i] = 1;
+                else {
+                    // if(comparision[i-1] == -1)
+                    //     rlt[i] = 2;
+                    // else
+                    //     rlt[i] = rlt[i-1] + 1;
+                    if(comparision[i-1] == 1 && rlt[i-1] == 0)
+                        rlt[i] = 2;
+                    else if(comparision[i-1] == 1 && rlt[i-1])
+                        rlt[i] = rlt[i-1] + 1;
+                }
+            }
+        }
+        for(int i = 0 ; i <length;i++)
+            if(!rlt[i]) rlt[i] = 1;
+        int sum = 0;
+        for(int i = 1; i < length ; i++){
+            sum += rlt[i];
+            cout<<rlt[i]<<' ';
+        }
+        cout<<endl;
+        sum+=1;
+        return sum;
+    }
+};
+int main(){
+    Solution sol;
+    vector<int> ex1 = {1,0,2};
+    cout<<sol.candy(ex1)<<endl;
+    vector<int> ex2 = {1,2,2};
+    cout<<sol.candy(ex2)<<endl;
+    vector<int> ex3 = {4,1,4,3,2,1,5,8,7,5,2};
+    cout<<sol.candy(ex3)<<endl;
+    vector<int> ex4 = {1,3,4,5,2};
+    cout<<sol.candy(ex4)<<endl;
+    return 0;
+}