1 #include<cstdio> 2 #include<cstring> 3 #include<queue> 4 #include<iostream> 5 #include<algorithm> 6 #define MAXN 10010 7 #define MAXM 20010 8 #define oo 0x7FFFFFFF 9 using namespace std; 10 int first[MAXN], next[MAXM], v[MAXM], cost[MAXM], e; 11 bool vis[MAXN]; 12 struct LCT { 13 int next[MAXN][2], pre[MAXN], val[MAXN], belong[MAXN], bef[MAXN], key[MAXN]; 14 void Init() { 15 memset(next, 0, sizeof(next)); 16 memset(pre, 0, sizeof(pre)); 17 val[0] = key[0] = -oo; 18 } 19 inline void PushUp(int x) { 20 val[x] = max(key[x], max(val[next[x][0]], val[next[x][1]])); 21 } 22 inline void Rotate(int x, int kind) { 23 int y, z; 24 y = pre[x]; 25 z = pre[y]; 26 next[y][!kind] = next[x][kind]; 27 pre[next[x][kind]] = y; 28 next[z][next[z][1] == y] = x; 29 pre[x] = z; 30 next[x][kind] = y; 31 pre[y] = x; 32 PushUp(y); 33 } 34 void Splay(int x) { 35 int rt; 36 for (rt = x; pre[rt]; rt = pre[rt]) 37 ; 38 if (rt != x) { 39 bef[x] = bef[rt]; 40 bef[rt] = 0; 41 while (pre[x]) { 42 if (next[pre[x]][0] == x) 43 Rotate(x, 1); 44 else 45 Rotate(x, 0); 46 } 47 PushUp(x); 48 } 49 } 50 void Access(int x) { 51 int father; 52 for (father = 0; x; x = bef[x]) { 53 Splay(x); 54 bef[next[x][1]] = x; 55 bef[father] = 0; 56 pre[next[x][1]] = 0; 57 next[x][1] = father; 58 pre[father] = x; 59 father = x; 60 PushUp(x); 61 } 62 } 63 int Query(int x, int y) { 64 Access(y); 65 for (y = 0; x; x = bef[x]) { 66 Splay(x); 67 if (!bef[x]) 68 return max(val[y], val[next[x][1]]); 69 bef[next[x][1]] = x; 70 bef[y] = 0; 71 pre[next[x][1]] = 0; 72 next[x][1] = y; 73 pre[y] = x; 74 y = x; 75 PushUp(x); 76 } 77 return 0; 78 } 79 void Change(int x, int y) { 80 int t; 81 t = belong[x - 1]; 82 key[t] = y; 83 Splay(t); 84 } 85 } lct; 86 int INT() { 87 int res; 88 char ch; 89 bool neg; 90 while (ch = getchar(), !isdigit(ch) && ch != '-') 91 ; 92 if (ch == '-') { 93 neg = true; 94 res = 0; 95 } else { 96 neg = false; 97 res = ch - '0'; 98 } 99 while (ch = getchar(), isdigit(ch)) 100 res = res * 10 + ch - '0'; 101 return neg ? -res : res; 102 } 103 char CHAR() { 104 char res, ch; 105 while (res = getchar(), !isalpha(res)) 106 ; 107 while (ch = getchar(), isalpha(ch)) 108 ; 109 return res; 110 } 111 inline void AddEdge(int x, int y, int val) { 112 v[e] = y; 113 cost[e] = val; 114 next[e] = first[x]; 115 first[x] = e++; 116 } 117 void BFS(int x) { 118 int i, y; 119 queue<int> q; 120 memset(vis, false, sizeof(vis)); 121 vis[x] = true; 122 q.push(x); 123 while (!q.empty()) { 124 x = q.front(); 125 q.pop(); 126 for (i = first[x]; i != -1; i = next[i]) { 127 y = v[i]; 128 if (!vis[y]) { 129 lct.bef[y] = x; 130 lct.key[y] = lct.val[y] = cost[i]; 131 lct.belong[i >> 1] = y; 132 vis[y] = true; 133 q.push(y); 134 } 135 } 136 } 137 } 138 int main() { 139 int c; 140 char ch; 141 int n, i; 142 int u, v, w; 143 c = INT(); 144 while (c--) { 145 lct.Init(); 146 n = INT(); 147 memset(first, -1, sizeof(first)); 148 for (e = 0, i = 1; i < n; i++) { 149 u = INT(), v = INT(), w = INT(); 150 AddEdge(u, v, w); 151 AddEdge(v, u, w); 152 } 153 BFS(1); 154 while (ch = CHAR(), ch != 'D') { 155 u = INT(), v = INT(); 156 if (ch == 'Q') 157 printf("%d\n", lct.Query(u, v)); 158 else 159 lct.Change(u, v); 160 } 161 } 162 return 0; 163 }
