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#include <bits/stdc++.h> |
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using namespace std; |
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inline int readchar() { |
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const int N = 4194304; |
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static char buf[N]; |
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static char *p = buf, *end = buf; |
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bool fin = 0; |
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if (fin) return EOF; |
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if (p == end) { |
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if ((end = buf + fread(buf, 1, N, stdin)) == buf) { |
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fin = 1; |
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return EOF; |
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} |
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p = buf; |
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} |
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return *p++; |
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} |
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inline bool isdigit(char ch) { return ch>='0' && ch<='9'; } |
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inline int readUInt() { |
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char ch; |
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unsigned int r=0; |
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while (!isdigit(ch=readchar())) |
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if (ch == EOF) return EOF; |
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r = ch-'0'; |
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while (isdigit(ch=readchar())) |
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r = (r<<3) + (r<<1) + ch-'0'; |
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while (ch!=' ' && ch!='\n') |
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ch = readchar(); |
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return r; |
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} |
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int E[51][51], S[51]; |
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void dfs(int u) { |
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for (int v=1; v<=50; ++v) |
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if (E[u][v]) { |
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--E[u][v]; --E[v][u]; |
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dfs(v); |
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cout << v << ' ' << u << "\n"; |
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} |
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} |
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char BUF[8000000]; |
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int main() { |
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cout.rdbuf()->pubsetbuf(BUF, 8000000); |
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ios_base::sync_with_stdio(0); |
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int T = readUInt(); |
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for (int cse=1; cse<=T; ++cse) { |
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int n = readUInt(); |
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if (cse > 1) cout << "\n"; |
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cout << "Case #" << cse << "\n"; |
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memset(E, 0, sizeof(E)); |
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memset(S, 0, sizeof(S)); |
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int mn = 100; |
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for (int i=0; i<n; ++i) { |
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int u = readUInt(), |
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v = readUInt(); |
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++E[u][v]; |
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++E[v][u]; |
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++S[u]; ++S[v]; |
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mn = min(mn, min(u, v)); |
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} |
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bool bad=0; |
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for (int u=1; u<=50; ++u) |
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if (S[u]&1) { |
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bad = 1; |
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break; |
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} |
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if (bad) cout << "some beads may be lost\n"; |
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else dfs(mn); |
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} |
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} |
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