TheAlgorithms/Java · error · IllegalArgumentException

Total nodes must be between 1 and + MAX_NODES

Error message

Total nodes must be between 1 and  + MAX_NODES

What it means

Thrown by PageRank.validateInputParameters (called during calculation) when totalNodes is outside [1, MAX_NODES] (MAX_NODES = 10). This is the same node-count invariant enforced at construction but applied to the calculate path; it protects the fixed-size internal buffers.

Source

Thrown at src/main/java/com/thealgorithms/others/PageRank.java:185

        if (verbose) {
            System.out.println("\nFinal PageRank:");
            printPageRanks(totalNodes);
        }

        return pageRankValues.clone();
    }

    /**
     * Validates input parameters for PageRank calculation
     *
     * @param totalNodes    the total number of nodes
     * @param dampingFactor the damping factor
     * @param iterations    number of iterations
     * @throws IllegalArgumentException if parameters are invalid
     */
    private void validateInputParameters(int totalNodes, double dampingFactor, int iterations) {
        if (totalNodes < 1 || totalNodes > MAX_NODES) {
            throw new IllegalArgumentException("Total nodes must be between 1 and " + MAX_NODES);
        }
        if (dampingFactor < 0 || dampingFactor > 1) {
            throw new IllegalArgumentException("Damping factor must be between 0 and 1");
        }
        if (iterations < 1) {
            throw new IllegalArgumentException("Iterations must be at least 1");
        }
    }

    /**
     * Initializes PageRank values for all nodes
     *
     * @param totalNodes      the total number of nodes
     * @param initialPageRank the initial PageRank value
     * @param verbose         whether to print output
     */
    private void initializePageRanks(int totalNodes, double initialPageRank, boolean verbose) {
        for (int i = 1; i <= totalNodes; i++) {

View on GitHub (pinned to fdfb9a395b)

Solutions

1. Keep totalNodes within [1, 10] and consistent with the nodeCount used at construction.
2. Source totalNodes from the same graph object used to build the PageRank instance.
3. Use a PageRank implementation without a hard cap for larger graphs.
4. Validate totalNodes at the boundary before invoking the calculation.

Example fix

// before
pageRank.calc(graph.size(), damping, iterations); // graph.size() may be > 10

// after
int total = Math.max(1, Math.min(graph.size(), 10));
pageRank.calc(total, damping, iterations);

if (totalNodes < 1 || totalNodes > 10) {
    throw new IllegalArgumentException("totalNodes must be in [1, 10]; got " + totalNodes);
}
pageRank.calc(totalNodes, dampingFactor, iterations);

public static boolean isSupportedNodeCount(int n) {
    return n >= 1 && n <= 10;
}

try {
    pageRank.calc(total, damping, iters);
} catch (IllegalArgumentException e) {
    total = Math.max(1, Math.min(total, 10));
    pageRank.calc(total, damping, iters);
}

When it happens

Trigger: Triggering a calculate/step that internally calls validateInputParameters with totalNodes < 1 or totalNodes > 10; mismatch between the constructed nodeCount and a totalNodes argument passed to a calculation entry point.

Common situations: Passing a totalNodes argument inconsistent with the constructed size; loading a graph with more than 10 nodes; calling calculate with parameters derived from a different graph than the one used at construction.

Related errors

• Number of nodes must be between 1 and + MAX_NODES
• Node index out of bounds
• Damping factor must be between 0 and 1
• Iterations must be at least 1
• Number of vertices must be positive

AI-assisted analysis of TheAlgorithms/Java@fdfb9a395b (2026-08-13). Data as JSON: /api/errors/110af38b45ed9714. Report an issue: GitHub.