Kmp算法
2014-04-08 20:30
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/* 时间复杂度O(a.length() + b.length()) 最小覆盖字串(len - next[len - 1] - 1) 单串模式匹配 */ void get_next(char* s) { next[0] = -1; for (int i = 1, j = -1; i < strlen(s); i++) { while (j >= 0 && s[i] != s[j + 1]) { j = next[j]; } if (s[i] == s[j + 1]) { j++; } next[i] = j; } } int kmp(char* a, char* b) { int res = 0, len = strlen(b); get_next(b); for (int i = 0, j = -1; i < strlen(a); i++) { while (j >= 0 && a[i] != b[j + 1]) { j = next[j]; } if (a[i] == b[j + 1]) { j++; } if (j == len - 1) { res++; j = next[j]; //计算有多少个 } } return res; }