刷题之Implement strStr()、Climbing Stairs

 public class Solution {

     public int strStr(String haystack, String needle) {

         int big = haystack.length();

         int sub = needle.length();

         if(big==0 && sub==0) return 0;

         if(big==0 && sub!=0) return -1;

         int index = big-sub;

         for(int i=0;i<=index;i++){

             if(haystack.substring(i,sub+i).equals(needle))return i;

         }

         return -1;

     }

 }

是int index = haystack.indexOf(needle)的另一种做法

Climbing Stairs

1）递归调用（容易内存溢出）：

 public class Solution {

     public int climbStairs(int n) {

         if(n<1)return 0;

         if(n==1)return 1;

         if(n==2)return 2;

         return climbStairs(n-1)+climbStairs(n-2);

     }

 }

2）类似斐波那契数列，开头1,2.代替1.1

 public class Solution {

     public int climbStairs(int n) {

         if(n<1)return 0;

         if(n==1)return 1;

         if(n==2)return 2;

         int nums = 0;

         int one = 1;

         int two = 2;

         for(int i=3;i<=n;i++){

             nums = one+two;

             one = two;

             two = nums;

         }

         return nums;

     }

 }

https://leetcode.com/problems/climbing-stairs/#/description

巴特西

刷题之Implement strStr()、Climbing Stairs

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