Descripition 給你一張圖，每次加一條邊，加完邊後，問這兩個點是否屬於同一個點雙，不是輸出No，否則輸出點雙的點數。

Sample Input 5 3 4 1 2 4 3 4 5 2 3 1 3 4 5 2 4

Sample Output No 3 2 5

對於每一次加邊，就相當於把當前樹上的一段合成一點，這個可用並差集搞。 問題是如何構造出一棵樹，這個也很簡單，一開始先加完所有的邊，建出一棵樹即可。

#include <cstdio>
#include <cstring>
#include <algorithm>
 


using namespace std;
int read() {
    int s = 0, f = 1; char ch = getchar();
    while(ch < '0' || ch > '9') {if(ch == '-') f = -1; ch = getchar();}
    while(ch >= '0' && ch <= '9') s = s * 10 + ch - '0', ch = getchar();
    return s * f;
}

struct node {
    int x, y;
} q1[210000], q2[210000
 
];
struct edge {
    int x, y, next;
} e[410000]; int len, last[210000];
int fa[210000], dep[210000], f[210000];
int ff[210000], tot[210000];

int findfa(int x) {
    if(fa[x] != x) fa[x] = findfa(fa[x]);
    return fa[x];
}

int findfa2(int x) {
    if(ff[x] != x) ff[x] = findfa2(ff[x]);
    return ff[x];
}

void Merge(int x, int
 
 y) {
    x = findfa2(x), y = findfa2(y);
    while(x != y) {
        if(dep[x] > dep[y]) swap(x, y);
        int fy = findfa2(f[y]);
        ff[y] = fy; tot[fy] += tot[y];
        y = fy;
    }
}

void ins(int x, int y) {
    e[++len].x = x; e[len].y = y;
    e[len].next = last[x]; last[x] = len;
}

void dfs(int x) {
    for(int k = last[x]; k; k = e[k].next) {
        int y = e[k].y;
        if(y != f[x]) f[y] = x, dep[y] = dep[x] + 1, dfs(y);
    }
}

int main() {
    int n = read(), m = read(), q = read();
    for(int i = 1; i <= n; i++) fa[i] = i;
    for(int i = 1; i <= m; i++) {
        int x = read(), y = read();
        int fx = findfa(x), fy = findfa(y);
        if(fx != fy)  ins(x, y), ins(y, x), fa[fx] = fy;
        q1[i].x = x, q1[i].y = y;
    }
    for(int i = 1; i <= q; i++) {
        int x = read(), y = read();
        int fx = findfa(x), fy = findfa(y);
        if(fx != fy)  ins(x, y), ins(y, x), fa[fx] = fy;
        q2[i].x = x, q2[i].y = y;
    } for(int i = 1; i <= n; i++) if(!dep[i]) dep[i] = 1, dfs(i);
    for(int i = 1; i <= n; i++) fa[i] = i, ff[i] = i, tot[i] = 1;
    for(int i = 1; i <= m; i++) {
        int x = q1[i].x, y = q1[i].y;
        int fx = findfa(x), fy = findfa(y);
        if(fx != fy) fa[fx] = fy;
        else Merge(x, y);
    }
    for(int i = 1; i <= q; i++) {
        int x = q2[i].x, y = q2[i].y;
        int fx = findfa(x), fy = findfa(y);
        if(fx != fy) fa[fx] = fy, printf("No\n");
        else Merge(x, y), printf("%d\n", tot[findfa2(x)]);
    }
    return 0;
}