题目:
Implement strStr(). Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack. Example 1: Input: haystack = "hello", needle = "ll" Output: 2 Example 2: Input: haystack = "aaaaa", needle = "bba" Output: -1 Clarification: What should we return when For the purpose of this problem, we will return 0 when |
实现 strStr() 函数。 给定一个 haystack 字符串和一个 needle 字符串,在 haystack 字符串中找出 needle 字符串出现的第一个位置 (从0开始)。如果不存在,则返回 -1。 示例 1: 输入: haystack = "hello", needle = "ll" 输出: 2 示例 2: 输入: haystack = "aaaaa", needle = "bba" 输出: -1 说明: 当 对于本题而言,当 |
思路:haystack从前往后查找。
class Solution {
public:
int strStr(string haystack, string needle) {
int m=haystack.size(),n=needle.size(),i,j,p=0;
if(n==0) return 0;
if(m<n) return -1;
for(i=0;i<=m-n;++i)
{
p=0;
for(j=0;j<n;++j)
{
if(haystack[i+j]==needle[j])
p++;
}
if(p==n) return i;
}
return -1;
}
};