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 ", 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 ", ans ); 130 } 131 return 0; 132 }