2125 very simple

2125-20240103-pass/main.cpp

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+#include<stdcpp.h>
+using namespace std;
+class Solution{
+    public:
+    int numberOfBeams(vector<string> & bank){
+        int len = bank.size();
+        vector<string> null_bank;
+        for(string row_plan: bank){
+            bool flag = 1;
+            for(char ch: row_plan){
+                if(ch == '1'){
+                    flag = 0;
+                    break;
+                }
+            }
+            if(!flag) null_bank.push_back(row_plan);
+        }
+        long long ans = 0;
+        int last = 0;
+        for(string row_plan: null_bank){
+            int num = 0;
+            for(char ch : row_plan){
+                if(ch == '1')   num++;
+            }
+            ans += num*last;
+            last = num;
+        }
+        return ans;
+    }
+    
+};
+
+int main(){
+    Solution sol;
+    vector<string> ex1 = {"011001","000000","010100","001000"};
+    cout<<"ex1"<<endl;
+    cout<<sol.numberOfBeams(ex1)<<endl;
+
+    vector<string> ex2 = {"000","000","000"};
+    cout<<"ex2"<<endl;
+    cout<<sol.numberOfBeams(ex2)<<endl;
+    return 0;
+}