GitHub Viewer
public class commonAlgorithm {
/**
* 判断一个数是否为素数
*
* @param num
* @return
*/
private static boolean isPrime(int num) {
if (num = arr.length)
throw new IllegalArgumentException("j is out of bound.");
Object temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
/**
* 求n的和
*
* @param n
* @return
*/
private static int sum(int n) {
if (n < 0)
throw new IllegalArgumentException("n should be greater or equal to zero.");
int ret = 0;
for (int i = 0; i 0)
l = mid + 1; // target在[mid+1...r)中; [l...mid]一定没有target
else // target < arr[mid]
r = mid; // target在[l...mid)中; [mid...r)一定没有target
}
return -1;
}
}