URAL 1517 Freedom of Choice

题目大意：

只有一个测例，测例中给出字符串长度N（1 ≤ N ≤ 100,000），接下来给出两个长度为N的字符串（都由大写字母组成），要求输出最长公共连续子序列。

题目链接

注释代码：

/*
* Problem ID : URAL 1517 Freedom of Choice
* Author     : Lirx.t.Una
* Language   : Visual C 2010
* Run Time   : 0.171
* Run Memory : 4232KB
*/

#pragma GCC optimize("O2")

#include <stdio.h>

#define	CHN			'Z'
#define	MAXN		200002

#define	MAX(x,y)	( (x) > (y) ? (x) : (y) )
#define	MIN(x,y)	( (x) < (y) ? (x) : (y) )

int		buf1[MAXN];
int		buf2[MAXN];
int		buf3[MAXN];

int		sa[MAXN];
int		h[MAXN];
int	*	rk;

char	s[MAXN];

int
keq( int *v, int x, int y, int l ) {

return v[x] == v[y] && v[x + l] == v[y + l];
}

void
bd_sa( char *s, int n, int mv ) {

int *	vi;
int	*	sv;
int	*	lv;
int	*	t;

int		v;
int		cl;

int		i, j;

vi = buf1;
sv = buf2;
lv = buf3;

for ( i = 0; i <= mv; i++ )	sv[i] = 0;
for ( i = 0; i <= n; i++ ) sv[ vi[i] = s[i] ]++;
for ( i = 1; i <= mv; i++ ) sv[i] += sv[i - 1];
for ( i = n; i >= 0; i-- ) sa[ --sv[ vi[i] ] ] = i;

for ( cl = 1, v = 0; v <= n; cl <<= 1, mv = v ) {

for ( j = 0, i = n - cl + 1; i <= n; i++ ) lv[j++] = i;
for ( i = 0; i <= n; i++ ) if ( sa[i] >= cl ) lv[j++] = sa[i] - cl;

for ( i = 0; i <= mv; i++ ) sv[i] = 0;
for ( i = 0; i <= n; i++ ) sv[ vi[ lv[i] ] ]++;
for ( i = 1; i <= mv; i++ ) sv[i] += sv[i - 1];
for ( i = n; i >= 0; i-- ) sa[ --sv[ vi[ lv[i] ] ] ] = lv[i];

for ( t = vi, vi = lv, lv = t, vi[ sa[0] ] = 0, v = 1, i = 1; i <= n; i++ )
vi[ sa[i] ] = keq( lv, sa[i - 1], sa[i], cl ) ? v - 1 : v++;
}

rk = vi;
}

void
bd_h( char *s, int n ) {

int		i, j;
int		cl;

for ( cl = 0, i = 0; i < n; h[ rk[i++] ] = cl )
for ( cl ? --cl : 0, j = sa[ rk[i] - 1 ]; s[i + cl] == s[j + cl]; cl++ );
}

int
main() {

int		len;//字符串长
int		n;//合并后的长度
int		ml;//maximum length，最长公共子串长度
int		ll;//lft link，左链接临时变量
int		lft, rht;//最长公共子串的左右区间

int		i;

scanf("%d", &len);
scanf("%s", s);
s[len] = '#';
scanf("%s", s + len + 1);
n = ( len << 1 ) + 1;

bd_sa( s, n, CHN );
bd_h( s, n );

for ( ml = 0, i = 1; i <= n; i++ )
if ( h[i] > ml )
if ( ( ll = MIN( sa[i - 1], sa[i] ) ) < len && MAX( sa[i - 1], sa[i] ) > len ) {

ml  = h[i];
lft = ll;//更新左边界
rht = lft + ml;//更新右边界
}

//直接输出，不要逐个输出
s[rht] = '\0';
puts(s + lft);

return 0;
}

无注释代码：

#pragma GCC optimize("O2")

#include <stdio.h>

#define	CHN			'Z'
#define	MAXN		200002

#define	MAX(x,y)	( (x) > (y) ? (x) : (y) )
#define	MIN(x,y)	( (x) < (y) ? (x) : (y) )

int		buf1[MAXN];
int		buf2[MAXN];
int		buf3[MAXN];

int		sa[MAXN];
int		h[MAXN];
int	*	rk;

char	s[MAXN];

int
keq( int *v, int x, int y, int l ) {

return v[x] == v[y] && v[x + l] == v[y + l];
}

void
bd_sa( char *s, int n, int mv ) {

int *	vi;
int	*	sv;
int	*	lv;
int	*	t;

int		v;
int		cl;

int		i, j;

vi = buf1;
sv = buf2;
lv = buf3;

for ( i = 0; i <= mv; i++ )	sv[i] = 0;
for ( i = 0; i <= n; i++ ) sv[ vi[i] = s[i] ]++;
for ( i = 1; i <= mv; i++ ) sv[i] += sv[i - 1];
for ( i = n; i >= 0; i-- ) sa[ --sv[ vi[i] ] ] = i;

for ( cl = 1, v = 0; v <= n; cl <<= 1, mv = v ) {

for ( j = 0, i = n - cl + 1; i <= n; i++ ) lv[j++] = i;
for ( i = 0; i <= n; i++ ) if ( sa[i] >= cl ) lv[j++] = sa[i] - cl;

for ( i = 0; i <= mv; i++ ) sv[i] = 0;
for ( i = 0; i <= n; i++ ) sv[ vi[ lv[i] ] ]++;
for ( i = 1; i <= mv; i++ ) sv[i] += sv[i - 1];
for ( i = n; i >= 0; i-- ) sa[ --sv[ vi[ lv[i] ] ] ] = lv[i];

for ( t = vi, vi = lv, lv = t, vi[ sa[0] ] = 0, v = 1, i = 1; i <= n; i++ )
vi[ sa[i] ] = keq( lv, sa[i - 1], sa[i], cl ) ? v - 1 : v++;
}

rk = vi;
}

void
bd_h( char *s, int n ) {

int		i, j;
int		cl;

for ( cl = 0, i = 0; i < n; h[ rk[i++] ] = cl )
for ( cl ? --cl : 0, j = sa[ rk[i] - 1 ]; s[i + cl] == s[j + cl]; cl++ );
}

int
main() {

int		len;
int		n;
int		ml;
int		ll;
int		lft, rht;

int		i;

scanf("%d", &len);
scanf("%s", s);
s[len] = '#';
scanf("%s", s + len + 1);
n = ( len << 1 ) + 1;

bd_sa( s, n, CHN );
bd_h( s, n );

for ( ml = 0, i = 1; i <= n; i++ )
if ( h[i] > ml )
if ( ( ll = MIN( sa[i - 1], sa[i] ) ) < len && MAX( sa[i - 1], sa[i] ) > len ) {

ml  = h[i];
lft = ll;
rht = lft + ml;
}

s[rht] = '\0';
puts(s + lft);

return 0;
}

单词解释：

Albania：阿尔巴尼亚，东欧国家

Albanian：阿尔巴尼亚人

bear with：vt, 忍受，宽容

democratic：adj, 民主的

presidential：adj, 总统的，首长的

politician：n, 政治家，政客

liberal：n, 自由主义者; adj, 自由主义的

conservative：n, 保守派; adj, 保守的

rival：n, 对手，竞争者

intention：n, 意图，目的

post：n, 岗位

compete：vt, 竞争，比赛

entertain：vt, 娱乐，款待

dirt：n, 污泥，污垢

cheer：n, 欢呼，愉快

approval：n, 认可，赞成，批准

occasion：n, 时机，场合

devote to：vt, 致力于，专注于

voter：n, 投票人

blame sb for sth：责备某人某事

opponent：n, 对手，反对派

corruption：n, 贪污，腐败

disrespect：n, 失礼，不敬

elder：n, 老人，长辈

terrorism：n, 恐怖主义

affiliation：n, 友好关系，联盟

socialist：n, 社会主义者; adj, 社会主义的

comrade：n, 同志（共产党的正式叫法）

fragment：n, 碎片，片段

identical：adj, 完全相同的