Unique Paths in a Grid?

Short answer: int UniquePaths(int m, int n) { int[,] dp = new int[m, n]; for (int i = 0; i < m; i++) dp[i, 0] = 1; for (int j = 0; j < n; j++) dp[0, j] = 1; for (int i = 1; i < m; i++) { for (int j = 1; j < n; j++) { dp[i, j] = dp[i - 1, j] + dp[i, j - 1]; } } return dp[m - 1, n - 1]; } Follow on:

Example code

int UniquePaths(int m, int n) {
int[,] dp = new int[m, n];
for (int i = 0; i < m; i++) dp[i, 0] = 1;
for (int j = 0; j < n; j++) dp[0, j] = 1;
for (int i = 1; i < m; i++) {
for (int j = 1; j < n; j++) {
dp[i, j] = dp[i - 1, j] + dp[i, j - 1];
}
}
return dp[m - 1, n - 1];
} Follow on:

Real-world example (ShopNest)

In coding rounds, state complexity aloud, write a clear ShopNest-flavored example (orders, carts), then handle edge cases (empty list, null, overflow).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.