简单题，主要为了练手。
1 #include <cstdio> 2 #include <iostream> 3 #define maxn 100010 4 using namespace std; 5 6 namespace L { 7 int pnt[maxn], pre[maxn], son[maxn][2], rtg[maxn], val[maxn], mxv[maxn]; 8 9 inline void update( int nd ) { 10 mxv[nd] = max( val[nd], max(mxv[son[nd][0]],mxv[son[nd][1]]) ); 11 } 12 void rotate( int nd, int d ) { 13 int p = pre[nd]; 14 int s = son[nd][!d]; 15 int ss = son[s][d]; 16 son[nd][!d] = ss; 17 son[s][d] = nd; 18 if( p ) son[p][ nd==son[p][1] ] = s; 19 else pnt[s] = pnt[nd]; 20 pre[nd] = s; 21 pre[ss] = nd; 22 pre[s] = p; 23 update(nd); 24 update(s); 25 } 26 void pushdown( int nd ) { 27 if( rtg[nd] ) { 28 int &ls=son[nd][0], &rs=son[nd][1]; 29 swap(ls,rs); 30 rtg[ls] ^= 1; 31 rtg[rs] ^= 1; 32 rtg[nd] = 0; 33 } 34 } 35 void bigpush( int nd ) { 36 if( pre[nd] ) bigpush(pre[nd]); 37 pushdown(nd); 38 } 39 void splay( int nd, int top=0 ) { 40 bigpush(nd); 41 while( pre[nd]!=top ) { 42 int p = pre[nd]; 43 int nl = nd==son[p][0]; 44 if( pre[p]==top ) { 45 rotate( p, nl ); 46 } else { 47 int pp = pre[p]; 48 int pl = p==son[pp][0]; 49 if( nl==pl ) { 50 rotate( pp, pl ); 51 rotate( p, nl ); 52 } else { 53 rotate( p, nl ); 54 rotate( pp, pl ); 55 } 56 } 57 } 58 } 59 void access( int nd ) { 60 int u = nd; 61 int v = 0; 62 while( u ) { 63 splay(u); 64 int s = son[u][1]; 65 pre[s] = 0; 66 pnt[s] = u; 67 pre[v] = u; 68 son[u][1] = v; 69 update(u); 70 v = u; 71 u = pnt[u]; 72 } 73 splay(nd); 74 } 75 void init( int n ) { 76 for( int i=0; i<=n; i++ ) 77 pnt[i] = pre[i] = son[i][0] = son[i][1] 78 = rtg[i] = val[i] = mxv[i] = 0; 79 } 80 void makeroot( int nd ) { 81 access(nd); 82 rtg[nd] ^= 1; 83 } 84 void link( int u, int v ) { 85 makeroot(u); 86 makeroot(v); 87 pnt[u] = v; 88 } 89 void inc_val( int nd, int w ) { 90 splay( nd ); 91 val[nd] += w; 92 update( nd ); 93 } 94 int qu_max( int u, int v ) { 95 makeroot(u); 96 access(v); 97 return max( val[v], mxv[son[v][0]] ); 98 } 99 }; 100 101 int n, q; 102 103 int main() { 104 scanf( "%d", &n ); 105 L::init(n); 106 for( int i=2,u,v; i<=n; i++ ) { 107 scanf( "%d%d", &u, &v ); 108 L::link(u,v); 109 } 110 scanf( "%d", &q ); 111 while( q-- ) { 112 char ch[10]; 113 int u, v, w; 114 scanf( "%s", ch ); 115 if( ch[0]=='I' ) { 116 scanf( "%d%d", &u, &w ); 117 L::inc_val(u,w); 118 } else { 119 scanf( "%d%d", &u, &v ); 120 printf( "%d ", L::qu_max(u,v) ); 121 } 122 } 123 }