ZOJ 7th Anniversary Contest

6/6

水了一场比赛，得空写个简单题解，分别是ZOJ3167-3172

传送门

题A ZOJ 3167

题意：貌似是给你m ^ n 的第k位为7的最小的n是什么？

题解：大数模拟吧，我懒得写~~

题B ZOJ3168

题意：先对Z排序，再对O，对J，对7，其他不变放在后面。

题解：水题，直接模拟。

/*zhen hao*/
#include <bits/stdc++.h>
using namespace std;

#define lson l, m, rt << 1
#define rson m + 1, r, rt << 1  1
#define ll long long

const int maxn = 1e3 + 10, maxm = 1e6 + 10;
int n, m, tot;
int head[maxn], dep[maxn];

struct Edge {
int v, next;
} edges[maxm];

void init() {
tot = 0;
memset(head, -1, sizeof head);
}

void add_edge(int u, int v) {
edges[tot] = (Edge){v, head[u]};
head[u] = tot++;
}

void dfs(int u, int fa, int d) {
dep[u] = max(dep[u], d);
for (int i = head[u]; i != -1; i = edges[i].next) {
int v = edges[i].v;
if (v == fa) continue;
dfs(v, u, d + 1);
}
}

int main() {
//  freopen("case.in", "r", stdin);
while (scanf("%d%d", &n, &m) == 2) {
init();
for (int i = 0; i < m; i++) {
int u, v;
scanf("%d%d", &u, &v);
add_edge(u, v);
add_edge(v, u);
}
memset(dep, 0, sizeof dep);
dfs(1, -1, 1);
int best = 0, bestid = 0;
for (int i = 0; i < n; i++) if (best < dep[i]) best = dep[bestid = i];
memset(dep, 0, sizeof dep);
dfs(bestid, -1, 1);
int temp = *max_element(dep, dep + n);
if (temp <= 7) puts("Impossible");
else printf("%d\n", temp);
}
return 0;
}

代码君