1 #include<cstdio> 2 #include<cstring> 3 #include<queue> 4 #include<iostream> 5 #define MAXN 50010 6 #define MAXM 100010 7 using namespace std; 8 int first[MAXN], next[MAXM], v[MAXM], cost[MAXM], e; 9 bool vis[MAXN]; 10 struct LCT { 11 int bef[MAXN], belong[MAXN]; 12 int next[MAXN][2], pre[MAXN], key[MAXN], sum[MAXN]; 13 void Init() { 14 memset(next, 0, sizeof(next)); 15 memset(pre, 0, sizeof(pre)); 16 } 17 inline void PushUp(int x) { 18 sum[x] = key[x] + sum[next[x][0]] + sum[next[x][1]]; 19 } 20 inline void Rotate(int x, int kind) { 21 int y, z; 22 y = pre[x]; 23 z = pre[y]; 24 next[y][!kind] = next[x][kind]; 25 pre[next[x][kind]] = y; 26 next[z][next[z][1] == y] = x; 27 pre[x] = z; 28 next[x][kind] = y; 29 pre[y] = x; 30 PushUp(y); 31 } 32 void Splay(int x) { 33 int rt; 34 for (rt = x; pre[rt]; rt = pre[rt]) 35 ; 36 if (rt != x) { 37 bef[x] = bef[rt]; 38 bef[rt] = 0; 39 while (pre[x]) { 40 if (next[pre[x]][0] == x) 41 Rotate(x, 1); 42 else 43 Rotate(x, 0); 44 } 45 PushUp(x); 46 } 47 } 48 void Access(int x) { 49 int father; 50 for (father = 0; x; x = bef[x]) { 51 Splay(x); 52 pre[next[x][1]] = 0; 53 bef[next[x][1]] = x; 54 next[x][1] = father; 55 pre[father] = x; 56 bef[father] = 0; 57 father = x; 58 PushUp(x); 59 } 60 } 61 void Change(int x, int val) { 62 int t; 63 t = belong[x - 1]; 64 key[t] = val; 65 Splay(t); 66 } 67 int Query(int x, int y) { 68 Access(y); 69 for (y = 0; x; x = bef[x]) { 70 Splay(x); 71 if (!bef[x]) 72 return sum[y] + sum[next[x][1]]; 73 pre[next[x][1]] = 0; 74 bef[next[x][1]] = x; 75 next[x][1] = y; 76 pre[y] = x; 77 bef[y] = 0; 78 y = x; 79 PushUp(x); 80 } 81 return 0; 82 } 83 } lct; 84 int INT() { 85 char ch; 86 int res; 87 while (ch = getchar(), !isdigit(ch)) 88 ; 89 for (res = ch - '0'; ch = getchar(), isdigit(ch);) 90 res = res * 10 + ch - '0'; 91 return res; 92 } 93 inline void AddEdge(int x, int y, int val) { 94 v[e] = y; 95 cost[e] = val; 96 next[e] = first[x]; 97 first[x] = e++; 98 } 99 void BFS(int x) { 100 int i, y; 101 queue<int> q; 102 memset(vis, false, sizeof(vis)); 103 vis[x] = true; 104 q.push(x); 105 while (!q.empty()) { 106 x = q.front(); 107 q.pop(); 108 for (i = first[x]; i != -1; i = next[i]) { 109 y = v[i]; 110 if (!vis[y]) { 111 lct.bef[y] = x; 112 lct.key[y] = lct.sum[y] = cost[i]; 113 lct.belong[i >> 1] = y; 114 vis[y] = true; 115 q.push(y); 116 } 117 } 118 } 119 } 120 int main() { 121 int n, m; 122 int u, v, w; 123 while (~scanf("%d%d", &n, &m)) { 124 lct.Init(); 125 memset(first, -1, sizeof(first)); 126 for (e = 0; --n;) { 127 u = INT(), v = INT(), w = INT(); 128 AddEdge(u, v, w); 129 AddEdge(v, u, w); 130 } 131 BFS(1); 132 while (m--) { 133 w = INT(), u = INT(), v = INT(); 134 if (w == 0) 135 lct.Change(u, v); 136 else 137 printf("%d\n", lct.Query(u, v)); 138 } 139 } 140 return 0; 141 }
