UVA315- Network(无向图割点)

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题目链接

题意：给出一张无向图，求割点的个数

思路：很裸的题目，直接套用模版即可。

代码：

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int MAXN = 1005;struct Edge{    int to, next;    bool cut;}edge[MAXN * 10];int head[MAXN], tot;int Low[MAXN], DFN[MAXN];int Index, cnt;bool cut[MAXN];void addedge(int u, int v) {    edge[tot].to = v;    edge[tot].next = head[u];    edge[tot].cut = false;    head[u] = tot++;}void Tarjan(int u, int pre) {    int v;    Low[u] = DFN[u] = ++Index;    int son = 0;    for (int i = head[u]; i != -1; i = edge[i].next) {        v = edge[i].to;        if (v == pre) continue;         if (!DFN[v]) {            son++;             Tarjan(v, u);             if (Low[u] > Low[v]) Low[u] = Low[v];            if (u != pre && Low[v] >= DFN[u]) {                cut[u] = true;             }        }         else if (Low[u] > DFN[v])            Low[u] = DFN[v];    }    if (u == pre && son > 1) cut[u] = true;}void init() {    memset(head, -1, sizeof(head));    memset(DFN, 0, sizeof(DFN));     memset(cut, false, sizeof(cut));     tot = 0;    Index = cnt = 0;}int main() {    int n;     while (scanf("%d", &n) && n) {        init();         int u, v;        while (scanf("%d", &u) && u) {            char ch;            while (scanf("%d%c", &v, &ch)) {                addedge(u, v);                 addedge(v, u);                 if (ch == '\n') break;            }                    }        for (int i = 1; i <= n; i++)            if (!DFN[i])                Tarjan(i, i);        for (int i = 1; i <= n; i++)            if (cut[i])                cnt++;        printf("%d\n", cnt);    }    return 0;}

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