直接使用递归的方法会导致TLE,加个缓存就好了:
public class Solution { private Integer[] buff = new Integer[1000]; /*
* @param n: an integer
* @return: an ineger f(n)
*/
public int fibonacci(int n) {
if(buff[n]!=null) return buff[n];
else if(n==1) return buff[1] = 0;
else if(n==2) return buff[2] = 1;
else return buff[n] = fibonacci(n-1) + fibonacci(n-2);
} }
或者使用迭代法:
public class Solution { /*
* @param n: an integer
* @return: an ineger f(n)
*/
public int fibonacci(int n) {
if(n==1) return 0;
else if(n==2) return 1; int a=0, b=1, c=a+b;
n-=2; while(n-->0){
c = a + b;
a = b;
b = c;
}
return c;
} }