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Author: MathProgrammer

Contests/AtCoder Beginner Contest 121/Explanations/Can You Solve This Explanation.txt

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+Calculate the Dot Product of every row of A with B and check for which rows A[i].B + C > 0
+
+-----
+
+#include <iostream>
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+
+int dot_product(vector <int> &A, vector <int> &B)
+{
+    int answer = 0;
+    for(int i = 1; i < A.size(); i++)
+    {
+        answer += A[i]*B[i];
+    }
+    return answer;
+}
+
+int main()
+{
+    int no_of_rows, no_of_columns, C;
+    cin >> no_of_rows >> no_of_columns >> C;
+
+    vector <int> B(no_of_columns + 1);
+    for(int i = 1; i <= no_of_columns; i++)
+    {
+        cin >> B[i];
+    }
+
+    vector <vector <int> > A(no_of_rows + 1, vector <int> (no_of_columns + 1));
+    for(int i = 1; i <= no_of_rows; i++)
+    {
+        for(int j = 1; j <= no_of_columns; j++)
+        {
+            cin >> A[i][j];
+        }
+    }
+
+    int good_rows = 0;
+    for(int i = 1; i <= no_of_rows; i++)
+    {
+        good_rows += (dot_product(A[i], B) + C > 0);
+    }
+
+    cout << good_rows << "\n";
+
+    return 0;
+}
+
+
+