OJ-Problems-Source/HDOJ/3430_autoAC.cpp

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#include <cstdio>
#include <cstring>
const int N = 520;
int a[N + 5], b[N + 5], ta[N + 5], tb[N + 5];
bool vis[N + 5];
long long m[N + 5], c[N + 5];
long long exgcd(long long a, long long b, long long &x, long long &y) {
if (!b) {
x = 1;
y = 0;
return a;
}
long long res = exgcd(b, a % b, y, x);
y -= a/b*x;
return res;
}
long long mod(long long a, long long b) {
long long res = a % b;
if (res < 0) res += b;
return res;
}
void solve(int n) {
memset(vis, false, sizeof(vis));
int cnt = 0;
for (int i = 1; i <= n; ++i)
if (!vis[i]) {
int num = 0, t = i;
while (!vis[t]) {
vis[t] = true;
ta[++num] = t;
tb[num] = b[t];
t = a[t];
}
bool same = false;
for (int i = 1; i <= num; ++i)
if (tb[i] == ta[1]) {
same = true;
int j = i, k = 1;
do {
if (tb[j] != ta[k]) same = false;
j = j % num + 1;
k = k % num + 1;
} while (i != j);
t = i;
break;
}
if (!same) {
printf("-1\n");
return;
}
m[++cnt] = num;
c[cnt] = (num - t + 1) % num;
}
n = cnt;
long long ans = c[1], LCM = m[1];
for (int i = 2; i <= n; ++i) {
long long x, y, g = exgcd(LCM, m[i], x, y);
if ((c[i] - ans) % g) {
printf("-1\n");
return;
}
ans = mod(ans + LCM*mod((c[i] - ans)/g*x, m[i]/g), LCM/g*m[i]);
LCM = LCM/g*m[i];
}
printf("%I64d\n", ans);
return;
}
int main() {
int n;
while (scanf("%d", &n), n) {
for (int i = 1; i <= n; ++i) scanf("%d", &a[i]);
for (int i = 1; i <= n; ++i) scanf("%d", &b[i]);
solve(n);
}
return 0;
}