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| #include <cstdio>
#define maxN 2000010
struct edge{ int x, y, g; } b[maxN << 1];
int len = 0;
int f[maxN][20], w[maxN][20];
int dep[maxN], dl[maxN], h[maxN];
int max (int x, int y)
{
return x > y ? x : y;
}
void ins (int x, int y)
{
len++;
b[len].x = x;
b[len].y = y;
b[len].g = h[x];
h[x] = len;
}
void bfs (int x)
{
int l = 1, r = 2;
dl[1] = x;
while(l < r)
{
int x = dl[l];
for(int i = h[x];i;i = b[i].g)
{
int y = b[i].y;
if(!dep[y])
{
f[y][0] = x;
w[y][0] = 1;
dep[y] = dep[x] + 1;
dl[r] = y;
r++;
}
}
l++;
}
}
int lca (int x, int y)
{
if(dep[x] < dep[y])
{
int t = x;
x = y;
y = t;
}
for(int i = 19;i >= 0; i--)
{
if(f[x][i] && dep[f[x][i]] >= dep[y])
{
x = f[x][i];
}
}
if(x == y)
{
return x;
}
for(int i = 19;i >= 0; i--)
{
if(f[x][i] && f[y][i] && f[x][i] != f[y][i])
{
x = f[x][i];
y = f[y][i];
}
}
return f[x][0];
}
int dis (int x, int y)
{
if(dep[x] < dep[y])
{
int t = x;
x = y;
y = t;
}
int ans = 0;
for(int i = 19;i >= 0; i--)
{
if(f[x][i] && dep[f[x][i]] >= dep[y])
{
ans += w[x][i];
x = f[x][i];
}
}
if(x == y)
{
return ans;
}
for(int i = 19;i >= 0; i--)
{
if(f[x][i] && f[y][i] && f[x][i] != f[y][i])
{
ans += w[x][i];
ans += w[y][i];
x = f[x][i];
y = f[y][i];
}
}
ans += w[x][0];
ans += w[y][0];
return ans;
}
int main ()
{
int n = 0, T = 0;
scanf("%d %d %*d", &n, &T);
for(int i = 1;i < n; i++)
{
int x = 0, y = 0;
scanf("%d %d", &x, &y);
ins(x, y);
ins(y, x);
}
int root = 1;
dep[root] = 1;
bfs(root);
for(int j = 1;j <= 19; j++)
{
for(int i = 1;i <= n; i++)
{
f[i][j] = f[f[i][j - 1]][j - 1];
w[i][j] = w[f[i][j - 1]][j - 1] + w[i][j - 1];
}
}
while(T--)
{
int A = 0, B = 0, C = 0;
scanf("%d %d %d", &A, &B, &C);
int fA = lca(A, B);
int fB = lca(A, C);
int fC = lca(B, C);
int depA = dep[fA];
int depB = dep[fB];
int depC = dep[fC];
int depMax = max(depA, max(depB, depC));
if(depA == depMax)
{
printf("%d\n", dis(fA, B) + 1);
}
else if(depB == depMax)
{
printf("%d\n", dis(fB, B) + 1);
}
else if(depC == depMax)
{
printf("%d\n", dis(fC, B) + 1);
}
}
return 0;
}
|