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Merged
merged 2 commits into from
Jun 15, 2025
Merged

[pull] master from wisdompeak:master #324

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237c620
Create binary_lift.cpp
wisdompeak Jun 15, 2025
cbf27c0
Update Readme.md
wisdompeak Jun 15, 2025
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1 change: 1 addition & 0 deletions Readme.md
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Original file line number Diff line number Diff line change
Expand Up @@ -1697,6 +1697,7 @@
[Graph](https://github.com/wisdompeak/LeetCode/tree/master/Template/Graph)
[Bit_Manipulation](https://github.com/wisdompeak/LeetCode/tree/master/Template/Bit_manipulation)
[RB_Tree](https://github.com/wisdompeak/LeetCode/tree/master/Template/RB_Tree)
[Binary_Lift](https://github.com/wisdompeak/LeetCode/tree/master/Template/Binary_Lift)
[二维子矩阵求和](https://github.com/wisdompeak/LeetCode/tree/master/Template/Sub_Rect_Sum_2D)
[二维差分数组](https://github.com/wisdompeak/LeetCode/tree/master/Template/Diff_Array_2D)
[CPP_LANG](https://github.com/wisdompeak/LeetCode/tree/master/Template/CPP_LANG)
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74 changes: 74 additions & 0 deletions Template/Binary_Lift/binary_lift.cpp
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@@ -0,0 +1,74 @@
using ll = long long;
const int MAXN = 100000;
const int LOGN = 17;
class Solution {
public:
vector<pair<int,int>> adj[MAXN];
int up[MAXN][LOGN+1];
int depth[MAXN];
ll distRoot[MAXN];

void dfs(int cur, int parent)
{
up[cur][0] = parent;
for(auto &[v,w]: adj[cur])
{
if(v == parent) continue;
depth[v] = depth[cur] + 1;
distRoot[v] = distRoot[cur] + w;
dfs(v, cur);
}
}

int lca(int a, int b)
{
if(depth[a] < depth[b]) swap(a,b);
int diff = depth[a] - depth[b];
for(int k = 0; k <= LOGN; k++){
if(diff & (1<<k)) a = up[a][k];
}
if(a == b) return a;
for(int k = LOGN; k >= 0; k--){
if(up[a][k] != up[b][k]){
a = up[a][k];
b = up[b][k];
}
}
return up[a][0];
}

ll dist(int a, int b)
{
int c = lca(a,b);
return distRoot[a] + distRoot[b] - 2*distRoot[c];
}

ll stepUp(int u, int k) {
for (int i=LOGN; i>=0; i--) {
if ((k>>i)&1) {
u = up[u][i];
}
}
return u;
}

void solve(vector<vector<int>>& edges) {
for (auto& edge: edges)
{
int u = edge[0], v = edge[1], w = edge[2];
adj[u].push_back({v,w});
adj[v].push_back({u,w});
}

depth[0] = 0;
distRoot[0] = 0;
dfs(0, 0);

for(int k = 1; k <= LOGN; k++) {
for(int v = 0; v < n; v++) {
up[v][k] = up[up[v][k-1]][k-1];
}
}

// Solve your problem.
}