1.描述
Implement strStr().
Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
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2.方法一
2.1分析
暴力匹配
2.2代码
int strStr(char* haystack, char* needle) {
if (NULL == haystack || NULL == needle) return -1;
unsigned int l1 = strlen(haystack);
unsigned int l2 = strlen(needle);
if (0 >= l2) return 0;
if (0 >= l1) return -1;
unsigned int i = 0, j = 0;
while (i < l1 && j < l2) {
if (haystack[i] == needle[j]) {
++i;
++j;
} else {
i = i - (j-1);
j = 0;
}
}
return j >= l2 ? i - l2 : -1;
}
3.方法二
3.1 分析
KMP 算法
