60 lines
959 B
C++
60 lines
959 B
C++
#include <iostream>
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#include <cstdio>
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using namespace std;
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const int MAXN = 100000;
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int g[MAXN]; //g[i]表示与i相连的边数
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int a[MAXN];
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void solve()
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{
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int n, m;
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scanf("%d%d", &n, &m);
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for (int i = 0; i < n; i++) {
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scanf("%d", &a[i]);
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g[i] = 0;
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}
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for (int i = 0; i < m; i++) {
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int u, v;
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scanf("%d%d", &u, &v);
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u--;
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v--;
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g[u]++;
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g[v]++;
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}
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int ods = 0; //奇点数
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int xors = 0;
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for (int i = 0; i < n; i++) {
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if (g[i] % 2) {
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ods++;
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if (g[i] % 3) {
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xors ^= a[i];
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}
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} else {
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if (g[i] % 4) {
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xors ^= a[i];
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}
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}
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}
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if (ods > 2) {
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puts("Impossible");
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return;
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}
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if (ods == 2) {
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printf("%d\n", xors);
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return;
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}
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int ans = 0;
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for (int i = 0; i < n; i++) {
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ans = max(ans, xors ^ a[i]);
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}
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printf("%d\n", ans);
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}
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int main()
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{
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//freopen("in.txt", "r", stdin);
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int t;
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scanf("%d", &t);
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while (t--) {
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solve();
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}
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}
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