Submission #21419

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
21419	2017-04-13T19:33:00 Z	gs14004	Quaternion inverse (kriii2_Q)	C++11	4 / 4	316 ms	2412 KB

Q

#include <bits/stdc++.h>
using namespace std;
typedef long long lint;
typedef long double llf;
typedef pair<int, int> pi;

int inv[100005], mod;

vector<vector<int>> aug;
vector<int> sol;

void solve(){
	vector<int> basis[4];
	vector<int> sol2 = {0, 0, 0, 0};
	for(int i=0; i<4; i++){
		bool ok = 0;
		for(int j=0; j<4; j++){
			if(aug[i][j]){
				if(basis[j].empty()){
					basis[j] = aug[i];
					sol2[j] = sol[i];
					ok = 1;
					break;
				}
				else{
					int c = mod - 1ll * aug[i][j] * inv[basis[j][j]] % mod;
					for(int k=0; k<4; k++){
						aug[i][k] += 1ll * c * basis[j][k] % mod;
						aug[i][k] %= mod;
					}
					sol[i] += 1ll * c * sol2[j] % mod;
					sol[i] %= mod;
				}
			}
		}
		if(!ok && sol[i]){
			puts("0 0 0 0");
			return;
		}
	}
	for(int i=3; i>=0; i--){
		if(!basis[i].empty()){
			for(int j=i+1; j<4; j++){
				sol2[i] += mod - 1ll * basis[i][j] * sol2[j] % mod;
				sol2[i] %= mod;
			}
			sol2[i] = 1ll * sol2[i] * inv[basis[i][i]] % mod;
		}
	}
	for(int i=0; i<4; i++){
		printf("%d ", sol2[i]);
	}
	puts("");
}

lint ipow(lint x, lint p){
	lint ret = 1, piv = x % mod;
	while(p){
		if(p&1) ret *= piv;
		piv *= piv;
		ret %= mod;
		piv %= mod;
		p >>= 1;
	}
	return ret % mod;
}

int main(){
	int t;
	cin >> mod >> t;
	for(int i=1; i<mod; i++) inv[i] = ipow(i, mod-2);
	while(t--){
		int a, b, c, d;
		scanf("%d %d %d %d",&a,&b,&c,&d);
		aug = {{a, -b, -c, -d}, {b, a, -d, c}, {c, d, a, -b}, {d, -c, b, a}};
		sol = {1, 0, 0, 0};
		for(int i=0; i<4; i++){
			for(int j=0; j<4; j++){
				aug[i][j] += mod;
				aug[i][j] %= mod;
			}
		}
		solve();
	}
}

Compilation message

Q.cpp: In function 'int main()':
Q.cpp:74:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d %d %d",&a,&b,&c,&d);
                                   ^

Subtask #1

1.0 / 1.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	0 ms	2412 KB	Output is correct
2	Correct	0 ms	2412 KB	Output is correct
3	Correct	0 ms	2412 KB	Output is correct
4	Correct	3 ms	2412 KB	Output is correct

Subtask #2

3.0 / 3.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	176 ms	2412 KB	Output is correct
2	Correct	219 ms	2412 KB	Output is correct
3	Correct	243 ms	2412 KB	Output is correct
4	Correct	239 ms	2412 KB	Output is correct
5	Correct	249 ms	2412 KB	Output is correct
6	Correct	246 ms	2412 KB	Output is correct
7	Correct	249 ms	2412 KB	Output is correct
8	Correct	253 ms	2412 KB	Output is correct
9	Correct	259 ms	2412 KB	Output is correct
10	Correct	263 ms	2412 KB	Output is correct
11	Correct	276 ms	2412 KB	Output is correct
12	Correct	279 ms	2412 KB	Output is correct
13	Correct	286 ms	2412 KB	Output is correct
14	Correct	316 ms	2412 KB	Output is correct
15	Correct	303 ms	2412 KB	Output is correct