2018 ACM-ICPC World Finals B.Comma Sprinkler

WF里面最简答一题，就是一个dfs就可以了，已经访问过的点可以不再访问

#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <vector>
using namespace std;
const int N = 1000005;
char s[1000005];

map<string, int> StoI;
vector<string> ItoS;
int tot = 0;
vector<int> result;
struct Node {
    int to, nx;
} E[N][2];
int head[N][2];
int tol[2] = {0, 0};

int tag[N][2];
int vis[N][2];

void add(int fr, int to) {
    E[tol[0]][0].to = to;
    E[tol[0]][0].nx = head[fr][0];
    head[fr][0] = tol[0]++;

    E[tol[1]][1].to = fr;
    E[tol[1]][1].nx = head[to][1];
    head[to][1] = tol[1]++;
}
void dfs(int x, int flag) {
    vis[x][flag] = 1;
    tag[x][flag]++;
    // printf("%d %d %s\n", x, flag, ItoS[x].c_str());
    for (int i = head[x][flag]; ~i; i = E[i][flag].nx) {
        int to = E[i][flag].to;
        if (vis[to][flag ^ 1])
            continue;
        dfs(to, flag ^ 1);
    }
}
int main() {
#ifdef LOCAL
    freopen("/Users/basasuya/ACM/in.txt", "r", stdin);
#endif
    int cnt = 0;
    memset(head, -1, sizeof(head));
    while (1) {
        s[cnt++] = getchar();
        if (s[cnt - 1] == -1 || s[cnt - 1] == '\n') {
            s[cnt - 1] = 0;
            break;
        }
    }
    int sLen = strlen(s);
    string tmp;
    ItoS.push_back(".");
    for (int i = 0; i < sLen; ++i) {
        if (s[i] == ' ' || s[i] == '.' || s[i] == ',') {
            if (!tmp.empty()) {
                if (StoI.find(tmp) == StoI.end()) {
                    ++tot;
                    StoI[tmp] = tot;
                    ItoS.push_back(tmp);
                }
                int Id = StoI[tmp];
                result.push_back(Id);
            }
            if (s[i] == '.')
                result.push_back(0);
            else if (s[i] == ',')
                result.push_back(-1);
            tmp.clear();
        } else
            tmp += s[i];
    }
    for (int i = 0, len = result.size(); i < len; ++i) {
        if (i >= 1 && result[i - 1] > 0 && result[i] > 0) {
            add(result[i - 1], result[i]);
        } else if (i >= 2 && result[i - 2] > 0 && result[i] > 0 && result[i - 1] == -1) {
            add(result[i - 2], result[i]);
            tag[result[i - 2]][0]++;
            tag[result[i]][1]++;
        }
    }
    for (int i = 1; i <= tot; ++i) {
        if (!vis[i][0] && tag[i][0]) {
            dfs(i, 0);
        }
        if (!vis[i][1] && tag[i][1]) {
            dfs(i, 1);
        }
    }

    for (int i = 0, len = result.size(), ok = 0; i < len; ++i) {
        if (i && result[i - 1] > 0 && result[i] > 0 && (tag[result[i - 1]][0] || tag[result[i]][1]))
            printf(",");
        if (result[i] < 0)
            printf(",");
        else if (result[i] == 0)
            printf(".");
        else {
            if (i)
                printf(" ");
            string& tmp = ItoS[result[i]];
            for (int j = 0, len = tmp.length(); j < len; ++j) {
                printf("%c", tmp[j]);
            }
        }
    }
}