编写一个程序输入一个n×n的矩阵，求出两条对角线的元素值之和

int main() { cout << "请输入n的值" << endl; int n, sum1 = 0, sum2 = 0; cin >> n; int** mat = new int* [n];//先分配n行空间 指向五个行指针(行) for (int i = 0; i < n; i++) { mat[i] = new int[n];//为第i个一维数组申请n个空间(列) } cout << "分配空间成功,请输入二维数组内容:" << endl; for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { cin >> mat[i][j]; } } cout << "初始分配二维数据如下:" << endl; for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { cout << mat[i][j] << " "; } cout << endl; } cout << "对角线相加和为: "; //正对角线 for (int i = 0; i < n; i++) { sum1 += mat[i][i]; } //反对角线 for (int j = 0; j < n; j++) { sum2 += mat[n - 1 - j][j]; } cout << sum1 + sum2 << endl; return 0; }