POJ 2528 Mayor's posters 线段树+离散化

离散化的时候，排序后相邻点差值大于1的话需要加点。

 

  1 #include <cstdio>

  2 #include <cstring>

  3 #include <cstdlib>

  4 #include <algorithm>

  5 

  6 #define lson l, m, rt << 1

  7 #define rson m + 1, r, rt << 1 | 1

  8 

  9 using namespace std;

 10 

 11 const int MAXN = 42222;

 12 

 13 struct node

 14 {

 15     int id;

 16     int a, b;

 17 };

 18 

 19 int n;

 20 int flag[ ( MAXN << 2 ) << 2 ];

 21 int color[ ( MAXN << 2 ) << 2 ];

 22 int val[ MAXN << 2 ];

 23 node Q[MAXN];

 24 bool vis[ MAXN << 2 ];

 25 

 26 void PushDown( int rt )

 27 {

 28     int lc = rt << 1;

 29     int rc = rt << 1 | 1;

 30     if ( flag[rt] != -1 )

 31     {

 32         flag[lc] = flag[rc] = flag[rt];

 33         color[lc] = color[rc] = flag[rt];

 34         flag[rt] = -1;

 35     }

 36     return;

 37 }

 38 

 39 void build( int l, int r, int rt )

 40 {

 41     color[rt] = -1;

 42     flag[rt] = -1;

 43     if ( l == r ) return;

 44     int m = ( l + r ) >> 1;

 45     build(lson);

 46     build(rson);

 47     return;

 48 }

 49 

 50 void Update( int L, int R, int c, int l, int r, int rt )

 51 {

 52     if ( L <= l && r <= R )

 53     {

 54         color[rt] = flag[rt] = c;

 55         return;

 56     }

 57     PushDown(rt);

 58     int m = ( l + r ) >> 1;

 59     if ( L <= m ) Update( L ,R, c, lson );

 60     if ( R > m ) Update( L ,R, c, rson );

 61     return;

 62 }

 63 

 64 int Query( int c, int l, int r, int rt )

 65 {

 66     if ( l == c && r == c )

 67         return color[rt];

 68 

 69     PushDown( rt );

 70     int m = ( l + r ) >> 1;

 71     if ( c <= m ) return Query( c, lson );

 72     else return Query( c, rson );

 73 }

 74 

 75 int main()

 76 {

 77     int T;

 78     scanf( "%d", &T );

 79     while ( T-- )

 80     {

 81         scanf( "%d", &n );

 82         int cnt = 0;

 83         for ( int i = 0; i < n; ++i )

 84         {

 85             scanf( "%d%d", &Q[i].a, &Q[i].b );

 86             val[ cnt++ ] = Q[i].a;

 87             val[ cnt++ ] = Q[i].b;

 88             Q[i].id = i + 1;

 89         }

 90         sort( val, val + cnt );

 91 

 92         int len = cnt;

 93         for ( int i = 1; i < len; ++i )

 94         {

 95             if ( val[i] - val[i - 1] > 1 )

 96             {

 97                 val[cnt++] = val[i] - 1;

 98             }

 99         }

100 

101         sort( val, val + cnt );

102         cnt = unique( val, val + cnt ) - val;

103 

104 //        for ( int i = 0; i < cnt; ++i )

105 //            printf( "%d ", val[i] );

106 //        puts("");

107 

108         build( 0, cnt - 1, 1 );

109 

110         for ( int i = 0; i < n; ++i )

111         {

112             int left = lower_bound( val, val + cnt, Q[i].a ) - val;

113             int right = lower_bound( val, val + cnt, Q[i].b ) - val;

114             //printf( "%d %d\n", left, right );

115             Update( left, right, Q[i].id, 0, cnt - 1, 1 );

116         }

117 

118         memset( vis, false, sizeof(vis) );

119         for ( int i = 0; i < cnt; ++i )

120         {

121             int ans = Query( i, 0, cnt - 1, 1 );

122             if ( ans != -1 ) vis[ans] = true;

123         }

124 

125         int ans = 0;

126         for ( int i = 1; i <= n; ++i )

127             if ( vis[i] ) ++ans;

128 

129         printf( "%d\n", ans );

130     }

131     return 0;

132 }