【JSOI2008】星球大战

本题在洛谷上的链接：https://www.luogu.org/problemnew/show/P1197

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也不算太难吧，正着想先建图再拆点不太好实现，不如先把所有数据读入，然后倒着添加点。

然后就是对代码能力和人品的考验了，，，一个小做法考虑的不好就导致只有10分。。。

#include <cstdio>

inline int get_num() {
    int num = 0;
    char c = getchar();
    while (c < '0' || c > '9') c = getchar();
    while (c >= '0' && c <= '9')
        num = num * 10 + c - '0', c = getchar();
    return num;
}

const int maxn = 4e5 + 5, maxm = 2e5 + 5;

int fa[maxn], head[maxn], eid;

struct Edge {
    int u, v, next;
} edge[2 * maxm];

inline void insert(int u, int v) {
    edge[++eid].u = u;
    edge[eid].v = v;
    edge[eid].next = head[u];
    head[u] = eid;
}

int dj_find(int i) {
    if (i == fa[i]) return i;
    else return fa[i] = dj_find(fa[i]);
}

inline void dj_merge(int a, int b) {
    a = dj_find(a), b = dj_find(b);
    if (a != b) fa[a] = b;
}

int vis[maxn], del[maxn], out[maxn];

int main() {
    int n, m, x, y, k, ans;
    n = get_num(), m = get_num();
    for (int i = 1; i <= m; ++i) {
        x = get_num(), y = get_num();
        insert(x, y);
        insert(y, x);
    }
    k = get_num();
    for (int i = 1; i <= k; ++i)
        vis[del[i] = get_num()] = 1;
    for (int i = 0; i < n; ++i) fa[i] = i;
    ans = n - k;
    for (int i = 0; i < n; ++i) {
        if (vis[i]) continue;
        for (int j = head[i]; j; j = edge[j].next) {
            int u = edge[j].u, v = edge[j].v;
            if (vis[v]) continue;
            if (dj_find(u) != dj_find(v)) {
                dj_merge(u, v);
                --ans;
            }
        }
    }
    out[k] = ans;
    for (int i = k; i >= 1; --i) {
        int u = del[i];
        vis[u] = 0, ++ans;
        for (int j = head[u]; j; j = edge[j].next) {
            int v = edge[j].v;
            if (vis[v]) continue;
            if (dj_find(u) != dj_find(v)) {
                dj_merge(u, v);
                --ans;
            }
        }
        out[i - 1] = ans;
    }
    for (int i = 0; i <= k; ++i) printf("%d
", out[i]);
    return 0;
}