HDU 4391 Paint The Wall

线段树

  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 = 100010;

 12 

 13 int N, Q;

 14 int color[ MAXN << 2 ]; //记录该区间的颜色

 15 int flag[ MAXN << 2 ];  //记录该区间是否是相同颜色

 16 int maxi[ MAXN << 2 ];  //记录区间最值，用于优化查询

 17 int mini[ MAXN << 2 ];

 18 

 19 void PushUp( int rt )

 20 {

 21     int lc = rt << 1;

 22     int rc = rt << 1 | 1;

 23 

 24     if ( flag[lc] && flag[rc] && color[lc] == color[rc] )

 25     {

 26         flag[rt] = 1;

 27         color[rt] = color[lc];

 28     }

 29     else

 30     {

 31         flag[rt] = 0;

 32         color[rt] = -1;

 33     }

 34 

 35     maxi[rt] = max( maxi[lc], maxi[rc] );

 36     mini[rt] = min( mini[lc], mini[rc] );

 37     return;

 38 }

 39 

 40 void PushDown( int rt )

 41 {

 42     int lc = rt << 1;

 43     int rc = rt << 1 | 1;

 44     if ( flag[rt] )

 45     {

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

 47         color[lc] = color[rc] = color[rt];

 48         maxi[lc] = maxi[rc] = color[rt];

 49         mini[lc] = mini[rc] = color[rt];

 50         flag[rt] = 0;

 51     }

 52     return;

 53 }

 54 

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

 56 {

 57     flag[rt] = 0;

 58     if ( l == r )

 59     {

 60         scanf( "%d", &color[rt] );

 61         flag[rt] = 1;

 62         maxi[rt] = mini[rt] = color[rt];

 63         return;

 64     }

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

 66     build( lson );

 67     build( rson );

 68     PushUp( rt );

 69     return;

 70 }

 71 

 72 void Update( int L, int R, int z, int l, int r, int rt )

 73 {

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

 75     {

 76         flag[rt] = 1;

 77         color[rt] = z;

 78         maxi[rt] = z;

 79         mini[rt] = z;

 80         return;

 81     }

 82     PushDown( rt );

 83 

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

 85     if ( L <= m ) Update( L, R, z, lson );

 86     if ( R > m ) Update( L, R, z, rson );

 87 

 88     PushUp(rt);

 89 

 90     return;

 91 }

 92 

 93 int Query( int L, int R, int z, int l, int r, int rt )

 94 {

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

 96     {

 97         if ( flag[rt] && color[rt] == z ) return r - l + 1;

 98         else if ( z < mini[rt] || z > maxi[rt] ) return 0;

 99     }

100     PushDown(rt);

101 

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

103     int ans = 0;

104     if ( L <= m ) ans += Query( L, R, z, lson );

105     if ( R > m ) ans += Query( L, R, z, rson );

106 

107     PushUp(rt);

108     return ans;

109 }

110 

111 int main()

112 {

113     while ( ~scanf( "%d%d", &N, &Q ) )

114     {

115         build( 0, N - 1, 1 );

116         while ( Q-- )

117         {

118             int a, l, r, z;

119             scanf( "%d%d%d%d", &a, &l, &r, &z );

120             if ( a == 1 ) Update( l, r, z, 0, N - 1, 1 );

121             else printf("%d\n", Query( l, r, z, 0, N - 1, 1 ) );

122         }

123     }

124     return 0;

125 }