因为最后要求的是区间和，所以其实color不用存下来，这里将color当做lazy标记：color为-1表示已经pushdown或为初始状态；color为1、2、3时表示区间为相应颜色。
1 #include <iostream> 2 #include <cstring> 3 #include <cstdio> 4 using namespace std; 5 6 const int N = 100001; 7 8 struct Node 9 { 10 int l, r, sum, color; 11 } node[N << 2]; 12 13 void build( int i, int l, int r ) 14 { 15 node[i].l = l, node[i].r = r, node[i].sum = r - l + 1, node[i].color = -1; 16 if ( l == r ) return ; 17 int mid = ( l + r ) >> 1; 18 build( i << 1, l, mid ); 19 build( i << 1 | 1, mid + 1, r ); 20 } 21 22 void pushup( int i ) 23 { 24 node[i].sum = node[i << 1].sum + node[i << 1 | 1].sum; 25 } 26 27 void pushdown( int i ) 28 { 29 if ( node[i].color != -1 ) 30 { 31 int lc = i << 1, rc = lc | 1; 32 node[lc].color = node[rc].color = node[i].color; 33 node[lc].sum = ( node[lc].r - node[lc].l + 1 ) * node[i].color; 34 node[rc].sum = ( node[rc].r - node[rc].l + 1 ) * node[i].color; 35 node[i].color = -1; 36 } 37 } 38 39 void update( int i, int l, int r, int c ) 40 { 41 if ( node[i].l == l && node[i].r == r ) 42 { 43 node[i].color = c; 44 node[i].sum = ( r - l + 1 ) * c; 45 return ; 46 } 47 pushdown(i); 48 int mid = ( node[i].l + node[i].r ) >> 1; 49 if ( r <= mid ) 50 { 51 update( i << 1, l, r, c ); 52 } 53 else if ( l > mid ) 54 { 55 update( i << 1 | 1, l, r, c ); 56 } 57 else 58 { 59 update( i << 1, l, mid, c ); 60 update( i << 1 | 1, mid + 1, r, c ); 61 } 62 pushup(i); 63 } 64 65 int main () 66 { 67 int t; 68 scanf("%d", &t); 69 for ( int _case = 1; _case <= t; _case++ ) 70 { 71 int n, m; 72 scanf("%d%d", &n, &m); 73 build( 1, 1, n ); 74 while ( m-- ) 75 { 76 int a, b, c; 77 scanf("%d%d%d", &a, &b, &c); 78 update( 1, a, b, c ); 79 } 80 printf("Case %d: The total value of the hook is %d. ", _case, node[1].sum); 81 } 82 return 0; 83 }