2014百度之星初赛第一轮解题报告：CycleCocycle

#include <cstdio>
#include <cstring>
#include <cmath>
#include <cassert>
#include <ctime>
#include <set>
#include <map>
#include <vector>
#include <string>
#include <bitset>
#include <sstream>
#include <iostream>
#include <algorithm>

using namespace std;

typedef long long ll;
typedef pair<int,int> PII;

#define fi first
#define se second
#define mp make_pair
#define pb push_back

#define N 1010

int TT, NN;
int n, m, S
;
bitset<N> a
;

int main () {
scanf("%d", &NN);
for (TT = 1; TT <= NN; TT++) {
scanf("%d%d", &n, &m);
for (int i = 0; i < n; i ++)
a[i].reset();
for (int i = 0; i < m; i ++) {
int x, y;
scanf("%d%d", &x, &y);
--x; --y;
a[x].set(y); a[y].set(x);
}
for (int i = 0; i < n; i++)
if (a[i].count() & 1) {
a[i].set(i);
a[i].set(N-1);
}
int rk = 0;
for (int i = 0; i < n; i ++) {
for (int j = rk; j < n; j ++)
if (a[j][i]) {
swap(a[j], a[rk]);
break;
}
if (!a[rk][i]) continue;
for (int j = rk+1; j < n; j ++)
if (a[j][i]) a[j] ^= a[rk];
rk ++;
}
memset(S, 0, sizeof S);
for (int i = rk-1; i >= 0; i --) {
int w = 0;
while (!a[i][w]) w ++;
if (a[i][N-1]) {
S[w] = 1;
for (int j = i-1; j >= 0; j -- )
if (a[j][w]) {
a[j][w] = 0;
a[j].flip(N-1);
}
}
w --;
}
printf("Case #%d:\n", TT);
for (int i = 0; i < n; i ++) printf("%d", S[i]);
puts ("");
}
return 0;
}