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What day is that day?
It's Saturday today, what day is it after 11 + 22 + 33 + ... + NNdays?
Input
There are multiple test cases. The first line of input contains an integer T indicating the number of test cases. For each test case:
There is only one line containing one integer N (1 <= N <= 1000000000).
Output
For each test case, output one string indicating the day of week.
Sample Input
2 1 2
Sample Output
Sunday Thursday
Hint
A week consists of Sunday, Monday, Tuesday, Wednesday, Thursday, Friday and Saturday.
找规律题的一种技巧
#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
using namespace std;
#define ll long long
const int N = 1e6 + 7;
const int M = 500;
const int mod = 7;
ll ksm(ll a, ll b, ll c) {
ll ans = 1;
a %= c;
while (b > 0) {
if (b&1) ans = (ans * a) % c;
a = a*a%c;
b>>=1;
}
return ans;
}
int sum[N];
int next_[N];
void print(int op) {
if (op == 1) {
puts("Monday");
} else if ( op == 2) {
puts("Tuesday");
} else if (op == 3) {
puts("Wednesday");
} else if (op == 4) {
puts("Thursday");
} else if (op == 5) {
puts("Friday");
} else if (op == 6) {
puts("Saturday");
} else {
puts("Sunday");
}
}
void get_next(int len) {
int i = 0, j = -1;
next_[0] = -1;
while (i <= len) {
if (j == -1 || sum[i] == sum[j]) {
++i, ++j;
next_[i] = j;
} else j = next_[j];
}
}
int main() {
sum[0] = 5;//因为是模7所以星期六是5、星期五是4...
for (int i = 1; i <= M; ++i) {
sum[i] = (ksm(i, i, mod) + sum[i-1]) % mod;
}
//printf ("%d\n", sum[294]); // 5
//get_next(M);
int t;
scanf ("%d", &t);
while (t--) {
int n;
scanf ("%d", &n);
print(sum[n%294]+1);
//getchar();
//暴力法找循环节
// for (int i = 1; i <= n; ++i) {
// int ok = 1;
// for (int j = 1; j <= i; ++j) {
// if (sum[j] != sum[i+j]) {
// ok=0;
// break;
// }
// }
// if (ok) {
// printf ("%d\n", i);
// break;
// }
// }
// kmp的next找循环节
//for (int i =1; i <= n; ++i) {
//printf ("%d\n", sum[i]);
//printf ("%d\n", next_[i]);
// int len = i - next_[i];
// if (len!=i && i%len == 0 ) {
// printf ("%d %d\n", i, i/len);
// break;
// }
//}
// puts("over");
}
return 0;
}