题目:
/******************************************************* * Finds and prints n prime integers * Jeff Offutt, Spring 2003 ******************************************************/ public static void printPrimes (int n) { int curPrime; // Value currently considered for primeness int numPrimes; // Number of primes found so far. boolean isPrime; // Is curPrime prime? int [] primes = new int [MAXPRIMES]; // The list of prime numbers. // Initialize 2 into the list of primes. primes [0] = 2; numPrimes = 1; curPrime = 2; while (numPrimes < n) { curPrime++; // next number to consider ... isPrime = true; for (int i = 0; i <= numPrimes-1; i++) { // for each previous prime. if (isDivisible(primes[i], curPrime)) { // Found a divisor, curPrime is not prime. isPrime = false; break; // out of loop through primes. } } if (isPrime) { // save it! primes[numPrimes] = curPrime; numPrimes++; } } // End while // Print all the primes out. for (int i = 0; i <= numPrimes-1; i++) { System.out.println ("Prime: " + primes[i]); } } // end printPrimes
流程图:
(b):将MAXPRIMES设为4,这样t2=(n=5)就会出现数组越界的错误,但t1=(n=3)无影响。
(c):n=0的时候不满足numPrimes < n,故不经过while循环
(d):点覆盖:{1,2,3,4,5,6,7,8,9,10,11,12,13,14}
边覆盖:{(1,2),(2,3),(2,12),(3,4),(4,5),(5,6),(6,7),(6,8),(7,5),(8,9), (5,9),(9,10),(9,11),(10,11),(11,2),(12,13),(13,14),(14,15),(15,13), (13,16)}
主路径覆盖:{(1,2,3,4,5,6,7),(1,2,3,4,5,6,8,9,10,11),(1,2,3,4,5,6,8,9,11),(1,2,3,4,5,9,10,11),(1,2,3,4,5,9,11),(1,2,12,13,14,15),(1,2,12,16),(3,4,5,6,8,9,10,11,2,12,13,14,15),
(3,4,5,6,8,9,11,2,12,13,14,15),(3,4,5,6,8,9,10,11,2,12,13,16),(3,4,5,6,8,9,11,2,12,13,16),(3,4,5,9,10,11,2,12,13,14,15),(3,4,5,9,11,2,12,13,14,15),(3,4,5,9,10,11,2,12,13,16),
(3,4,5,9,11,2,12,13,16),(6,7,5,9,10,11,2,12,13,14,15),(6,7,5,9,11,2,12,13,14,15),(6,7,5,9,10,11,2,12,13,16),(6,7,5,9,11,2,12,13,16),(14,15,13,16),(13,14,15,13),(5,6,7,5),
(2,3,4,5,6,8,9,10,11,2),(2,3,4,5,6,8,9,11,2),(2,3,4,5,9,10,11,2),(2,3,4,5,9,11,2)}