#include <iostream> #include <vector> using namespace std; int diagonalSum(vector<vector<int>>& matrix) { int n = matrix.size(); int sum = 0; for (int i = 0; i < n; i++) { sum += matrix[i][i] + matrix[i][n - i - 1]; } if (n % 2 == 1) { sum -= matrix[n / 2][n / 2]; } return sum; } int main() { vector<vector<int>> matrix = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; int sum = diagonalSum(matrix); cout << sum << endl; // 输出 25 return 0; }