Codeforces 536B Tavas and Malekas for overlapping positions KMP

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Test instructions

Constructing n-long strings with lowercase letters S,M requirements

String P

below M position. A1, A2 AM (Input ordered)

To cause the string s to start with AI and followed by a P-string.

Number of methods to ask for construction

Ideas:

In fact, for AI, ai+1, two positions, if these two positions interact (i.e. Ai+1-ai < Len)

Copy a P-like string P '

Put p in the AI position, put P ' in the ai+1 position, then only need to determine whether the second half of P is matched to the first half of P '.

Which position of P ' is the same as the tail of p.

KMP find these positions in the set.

And then it's a simple judgment.

#include <stdio.h> #include <string.h> #include <string> #include <math.h> #include <map> #include <vector> #include <set> #include <algorithm> #include <iostream>using namespace std; Template <class t>inline BOOL Rd (T &ret) {char c; int sgn;if (c = GetChar (), c = = EOF) return 0;while (c! = '-') && (c< ' 0 ' | | c> ' 9 ')) C = GetChar (); sgn = (c = = '-')? -1:1;ret = (c = = '-')? 0: (C-' 0 '); while (c = GetChar (), C >= ' 0 ' &&c <= ' 9 ') ret = ret * + (C-' 0 '); ret *= Sgn;return 1;} Template <class t>inline void pt (T x) {if (x <0) {Putchar ('-'); x = x;} if (x>9) pt (X/10);p Utchar (x% 10 + ' 0 ');} typedef long Long Ll;typedef unsigned long long ull;typedef pair<int, int> pii;const int N = 1e6 + 10;const int mod = 1e9 + 7;int f2[n], Len;char s1[n], s2[n];void getfail (int *f, char *p) {f[0] = f[1] = 0;for (int i = 1; i < Len; i++) { Int J = f[i];while (J&&p[i]! = p[j]) j = f[j];f[i + 1] = P[i] = = P[j]? j + 1:0;}} Set<int>s;void KMP (int *f, char *s1, char *s2) {getfail (f, S2); int j = 0, i = 0;while (i <= len) {while (J &&am P S1[i]! = s2[j]) j = f[j];i++, j + +;} for (int i = len; f[i]; i = f[i]) S.insert (Len-f[i]);} int m, N;bool v[n];int main () {while (CIN >> N) {rd (M); scanf ('%s ', S1), while (m--) {int u; RD (U); v[u] = true;} Len = strlen (S1); memcpy (S2, s1, sizeof S1); KMP (F2, S1, S2); ll ans = 1;for (int i = 1, last = -1e7; I <= n; i++) {if (v[i] = False && i-last >= len) {A NS *= 26ll;if (ans >= mod) ans%= mod;} else if (v[i] = True) {if (I-last < len &&!s.count (i-last)) {ans = 0; break;} last = i;}} PT (ANS%MOD); Puts ("");} return 0;}

Codeforces 536B Tavas and Malekas for overlapping positions KMP