_1572.java

packagecom.fishercoder.solutions.secondthousand;

importjava.util.HashSet;
importjava.util.Set;

publicclass_1572 {
publicstaticclassSolution1 {
publicintdiagonalSum(int[][] mat) {
intm = mat.length;
Set<Integer> added = newHashSet<>();
intsum = 0;
for (inti = 0; i < m; i++) {
for (intj = 0; j < m; j++) {
if (i == j) {
added.add(i * m + j);
sum += mat[i][j];
 }
 }
 }
for (inti = 0; i < m; i++) {
for (intj = m - 1; j >= 0; j--) {
if (i + j == m - 1 && added.add(i * m + j)) {
sum += mat[i][j];
 }
 }
 }
returnsum;
 }
 }
}