import org.apache.commons.lang3.time.DurationFormatUtils;
import org.apache.commons.lang3.time.DateUtils;
public static String getDurationTime(Date begin, Date end) {
String format = "";
long durationTime = end.getTime() - begin.getTime();
if (durationTime < DateUtils.MILLIS_PER_MINUTE) {
format = "s秒";
} else if (durationTime <= DateUtils.MILLIS_PER_HOUR) {
format = "m分鐘s秒";
} else if (durationTime <= DateUtils.MILLIS_PER_DAY) {
format = "H小時m分鐘s秒";
} else {
format = "d天H小時m分鐘s秒";
}
return DurationFormatUtils.formatDuration(durationTime, format);
}
2. 求最大公約數(shù)
public static int gcd(int p, int q) {
if (q == 0)
return p;
int r = p % q;
return gcd(q, r);
}
3. 二分查找
//數(shù)組a需要提前排序
public static int rank(int key, int[] a) {
int lo = 0;
int hi = a.length - 1;
while (lo <= hi) {
int mid = lo + (hi - lo) / 2;
if (key < a[mid])
hi = mid - 1;
else if (key > a[mid])
lo = mid + 1;
else
return mid;
}
return -1;
}
4. 判斷一個數(shù)是不是素數(shù)
public static boolean isPrime(int N) {
if (N < 2)
return false;
for (int i = 2; i * i <= N; i++)
if (N % i == 0)
return false;
return true;
}
5. 求平方根的算法
public static double sqrt(double c) {
if (c < 0.0)
return Double.NaN;
double err = 1e-15;
double t = c;
while (Math.abs(t - c / t) > err * t)
t = (c / t + t) / 2.0;
return t;
}
