Finished part 2 of day 7, still binary search with a slightly harder cost function

advent_of_code/d7/main.cpp

@@ -15,6 +15,17 @@ int fuel_cost(int n){
     return result;
 }
 
+int updated_fuel_cost(int n){
+    int result = 0;
+
+    for(auto &crab : crab_pos){
+        int dif = abs(crab - n);
+        result += dif * (dif + 1) / 2;
+    }
+    
+    return result;
+}
+
 int main(){
     ios::sync_with_stdio(0);
     cin.tie(0);
@@ -38,6 +49,27 @@ int main(){
     int target_coord = min(m2, m1);
     cout << fuel_cost(target_coord) << endl;
 
+    upper = crab_pos.back();
+    lower = crab_pos.front();
+    m1 = (upper + lower) / 2;
+    m2 = (upper + lower) / 2 + 1;
+
+    while(upper - lower > 1){
+        if(updated_fuel_cost(m1) < updated_fuel_cost(m2)){
+            upper = m1;
+        } else{
+            lower = m2;
+        }
+
+        m1 = (upper + lower) / 2;
+        m2 = (upper + lower) / 2 + 1;
+
+        // cout << m1 << ", fuel: " << updated_fuel_cost(m1) << "   " << m2 << ", fuel: " << updated_fuel_cost(m2) << endl;
+    }
+
+    target_coord = min(m1, m2);
+    cout << updated_fuel_cost(target_coord) << endl;
+
     cout << flush;
 
     return 0;