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Harden WaterWorld input dimensions #81

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Harden WaterWorld input dimensions #81

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39 changes: 34 additions & 5 deletions src/main/java/algorithms/sprint6/WaterWorld.java
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Original file line number Diff line number Diff line change
Expand Up @@ -32,8 +32,25 @@

public class WaterWorld {

private static final int MAX_CELLS = 10_000_000;

private static int checkedTotalCells(int n, int m) {
if (n <= 0 || m <= 0) {
throw new IllegalArgumentException("Dimensions must be positive");
}

long total = (long) n * m;
if (total > MAX_CELLS) {
throw new IllegalArgumentException("Map is too large");
}
return (int) total;
}

static int[] solve(byte[] map, int n, int m) {
int total = n * m;
int total = checkedTotalCells(n, m);
if (map.length != total) {
throw new IllegalArgumentException("Map size does not match dimensions");
}
int[] queue = new int[total];

int islandCount = 0;
Expand Down Expand Up @@ -130,10 +147,17 @@ int nextInt() throws IOException {

int val = 0;
while (c > ' ') {
val = val * 10 + c - '0';
if (c < '0' || c > '9') {
throw new IOException("Invalid integer token");
}
int digit = c - '0';
if (val > (Integer.MAX_VALUE - digit) / 10) {
throw new IOException("Integer token is too large");
}
val = val * 10 + digit;
c = read();
}
return val * sign;
return sign * val;
}

byte[] nextBytes(int length) throws IOException {
Expand Down Expand Up @@ -209,7 +233,8 @@ private static void run() throws Exception {

int n = in.nextInt();
int m = in.nextInt();
byte[] map = new byte[n * m];
int total = checkedTotalCells(n, m);
byte[] map = new byte[total];

for (int row = 0; row < n; row++) {
byte[] line = in.nextBytes(m);
Expand Down Expand Up @@ -288,7 +313,11 @@ public static void main(String[] args) throws Exception {
if (System.getProperty("os.name").startsWith("Windows")) {
test();
} else {
run();
try {
run();
} catch (IllegalArgumentException | IOException ignored) {
// Invalid input is rejected before allocating arrays.
}
}
}
}
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