CCPC-Wannafly Summer Camp 2019 全记录

 // 7.19-7.29 东北大学秦皇岛校区十天训练营，题目都挂在了Vjudge上。训练期间比较忙，没空更博总结，回来继续补题消化。

 // https://vjudge.net/contest/312902

https://vjudge.net/contest/313217

https://vjudge.net/contest/313584

https://vjudge.net/contest/314412

https://vjudge.net/contest/314730

https://vjudge.net/contest/314974

Day1

这天授课主题是简单图论，节奏挺好，wls两小时理完图论里的基本知识点。

下午的赛题就偏入门了（简单图论无疑），只涉及到最短路问题和简单的搜索以及一些奇怪的技巧。（差分约束呢？最小生成树呢？强连通分量呢？）

A - Jzzhu and Cities （补）

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#include<vector>
using namespace std;
typedef long long ll;
const int maxn = 200010;
struct Edge {
    int to;
    bool istrain;
    ll w;
    Edge(int v, bool is, ll ww):to(v), istrain(is), w(ww){}
    bool operator<(const Edge& a)const {
        if(w==a.w) return istrain;  // 非火车节点先更新
        return w > a.w;
    }
};
vector<Edge> G[maxn];

bool vis[maxn];
int d[maxn];

int Dijkstra() {
    memset(d, 0x3f, sizeof(d));
    memset(vis, 0, sizeof(vis));
    d[1] = 0;
    int res = 0;

    priority_queue<Edge> q;
    q.push(Edge(1, 0, 0));
    while(!q.empty()) {
        Edge tmp = q.top(); q.pop();
        int u = tmp.to;
        if(vis[u]) continue;

        vis[u] = 1;
    //    d[u] = tmp.w;
        if(tmp.istrain) ++res;

        for(int i=0;i<G[u].size();i++) {
            int v = G[u][i].to;
            if(!vis[v] && d[v]>=d[u]+G[u][i].w) {
                d[v] = d[u] + G[u][i].w;
                q.push(Edge(v, G[u][i].istrain, d[v]));
            }
        }

    }
    return res;

}

int main() {
    int n, m, k;
    cin>>n>>m>>k;
    int u, v, w;
    for(int i=0;i<m;i++) {
        scanf("%d %d %d", &u, &v, &w);
        G[u].push_back(Edge(v, 0, w));
        G[v].push_back(Edge(u, 0, w));
    }
    for(int i=0;i<k;i++) {
        scanf("%d %d", &v, &w);
        G[1].push_back(Edge(v, 1, w));
        // G[v].push_back(Edge(1, 1, w));
    }

    printf("%d\n", k-Dijkstra());

    return 0;
}

View Code

B - Phillip and Trains  BFS 注意打标记！！！（虽然只是3*100的地图也要爆内存！）

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
int n, k, sx;
char mp[3][110];
bool vis[3][110];
struct node {
    int x, y;
    node(int _x, int _y):x(_x), y(_y) {}
};

bool check(int x, int y) {
    if(x<0 || x>2)
        return false;
    if(y>=n)
        return true;
    if(mp[x][y]=='.')
        return true;

    return false;
}

bool bfs() {
    queue<node> q;
    q.push(node(sx, 0));

    while(q.size()) {
        node now = q.front(); q.pop();
        if(now.y>=n) {
            return true;
        }

    //    printf("(%d,%d) -> ", now.x, now.y);
        
        int nx = now.x, ny = now.y+1;
        if(!check(nx, ny))  continue; // 向右走一步

        for(int i=-1;i<=1;i++) {      // 尝试三个方向移动
            nx = now.x + i;
            if(check(nx, ny) && check(nx, ny+1) && check(nx, ny+2) && !vis[nx][ny+2]) {
                q.push(node(nx, ny+2));
                vis[nx][ny+2] = 1;
            }
        }
    }
    return false;
}


int main() {
    int t; cin>>t;
    while(t--) {
        scanf("%d %d", &n, &k);
        getchar();
        memset(vis, 0, sizeof(vis));
        for(int i=0;i<3;i++) {
            scanf("%s", mp[i]);
            
            if(mp[i][0]=='s')
                sx = i;
            
        }
        printf("%s\n", bfs()?"YES":"NO");
    }
    
    return 0;
}

View Code

Day2

Day3

Day4

Day5

Day6