NC232778 [模板]KMP字符串匹配

https://ac.nowcoder.com/acm/contest/view-submission?submissionId=50597340

NowCoder/232778/232778.cpp

@@ -0,0 +1,37 @@
+#pragma GCC optimize("Ofast")
+
+#include <iostream>
+#include <string>
+
+using std::cin;
+using std::cout;
+#define endl '\n'
+
+const int N = 1000005;
+
+int f[N], next[N];
+std::string s1, s2;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin >> s1 >> s2;
+    next[0] = -1;
+    for (int i = 1, j = -1; i < s2.size(); i++) {
+        while (j != -1 && s2[i] != s2[j + 1]) j = next[j];
+        if (s2[i] == s2[j + 1]) j++;
+        next[i] = j;
+    }
+    for (int i = 0, j = -1; i < s1.size(); i++) {
+        while (j != -1 && (j == s2.size() || s1[i] != s2[j + 1])) j = next[j];
+        if (s1[i] == s2[j + 1]) j++;
+        if (j == s2.size() - 1) {
+            cout << i - j + 1 << endl;
+            f[i] = j;
+        }
+    }
+    for (int i = 0; i < s2.size(); i++) {
+        cout << next[i] + 1 << ' ';
+    }
+    cout << endl;
+    return 0;
+}