94 lines
2.5 KiB
C++
94 lines
2.5 KiB
C++
#include <cstdio>
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#include <cstring>
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#include <algorithm>
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#define PI pair<int, int>
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#define MP make_pair
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#define x first
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#define y second
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const int maxn = 100100;
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using namespace std;
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int N, m;
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inline bool in( int x, int y )
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{
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return x >= -m && x <= m && y >= -m && y <= m;
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}
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PI p[maxn];
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PI a[maxn], b[maxn], c[maxn], d[maxn];
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int ea, eb, ec, ed;
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bool chk()
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{
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int i, j, k;
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ea = eb = ec = ed = -1;
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for( i = 0; i < N; ++i )
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{
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if( in(p[i].x+m, p[i].y-m) )
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{
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while( ea >= 0 && a[ea].y >= p[i].y-m ) ea--;
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if( ea >= 0 && a[ea].x==p[i].x+m ) continue;
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a[++ea] = MP(p[i].x+m, p[i].y-m);
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}
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if( in(p[i].x+m, p[i].y+m) )
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{
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while( eb >= 0 && b[eb].y <= p[i].y+m ) eb--;
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if( eb >= 0 && b[eb].x==p[i].x+m ) continue;
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b[++eb] = MP(p[i].x+m, p[i].y+m);
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}
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}
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for( i = N-1; i >= 0; --i )
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{
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if( in(p[i].x-m, p[i].y-m) )
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{
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while( ec >= 0 && c[ec].y >= p[i].y-m ) ec--;
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if( ec >= 0 && c[ec].x==p[i].x-m ) continue;
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c[++ec] = MP(p[i].x-m, p[i].y-m);
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}
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if( in(p[i].x-m, p[i].y+m) )
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{
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while( ed >= 0 && d[ed].y <= p[i].y+m ) ed--;
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if( ed >= 0 && d[ed].x==p[i].x-m ) continue;
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d[++ed] = MP(p[i].x-m, p[i].y+m);
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}
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}
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int na = 0, nb = 0, nc = ec+1, nd = ed+1;
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int v1, v2;
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for( i = -m; i <= m; ++i )
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{
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if( nc > 0 && c[nc-1].x == i ) nc--;
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if( nd > 0 && d[nd-1].x == i ) nd--;
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v1 = m+1, v2 = -m-1;
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if( na <= ea ) v1 = min(v1, a[na].y);
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if( nb <= eb ) v2 = max(v2, b[nb].y);
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if( nc <= ec ) v1 = min(v1, c[nc].y);
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if( nd <= ed ) v2 = max(v2, d[nd].y);
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if( v1-1 > v2 ) return 0;
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if( na <= ea && a[na].x == i ) na++;
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if( nb <= eb && b[nb].x == i ) nb++;
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}
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return 1;
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}
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int main()
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{
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int i, j, k, cases = 1;
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int ll, rr;
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while( scanf("%d", &N), N+1 )
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{
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for( i = 0; i < N; ++i )
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scanf("%d %d", &p[i].x, &p[i].y);
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sort(p, p+N);
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ll = -1, rr = 1000000;
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while( rr-ll > 1 )
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{
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m = (ll+rr)/2;
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if( chk() )
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rr = m;
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else
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ll = m;
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}
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m = rr;
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printf("Case %d: ", cases++);
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if( chk() ) printf("%d\n", rr);
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else puts("never");
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}
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return 0;
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}
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