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Primality test

C++ Algorithms

loop with early return

Flowchart (ISO 5807)

YesNoYesNoStartInput nn < 2Return falseEndi = 2, i * i <= n, i++n % i == 0Return falseEndReturn trueEndFigure 1 — isPrime

Source code

bool isPrime(int n) {
    if (n < 2) return false;
    for (int i = 2; i * i <= n; i++) {
        if (n % i == 0) return false;
    }
    return true;
}