34 lines
830 B
C++
34 lines
830 B
C++
#include <string>
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#include <vector>
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#include <iostream>
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/**
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* 28. Find the Index of the First Occurrence in a String
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*
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* Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
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*/
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class Solution {
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public:
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static int strStr(const std::string& s, const std::string& t) {
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const int m = s.length(), n = t.length();
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std::vector<int> p(n);
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for (int i = 1; i < n; ++i) {
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int j = p[i - 1];
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for (; j > 0 && t[i] != t[j]; j = p[j - 1]);
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p[i] = j + (t[i] == t[j]);
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}
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for (int i = 0, j = 0; i < m; ++i) {
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for (; j > 0 && s[i] != t[j]; j = p[j - 1]);
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if (s[i] == t[j] && ++j >= n)
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return i - j + 1;
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}
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return -1;
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}
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};
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int main() {
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std::cout << Solution::strStr("busasasasasapsadpp", "sasasasapsad");
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return 0;
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}
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