洛谷 P3825 [NOI2017]游戏

传送门

同 AcWing 1032 游戏

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using p = pair<int, int>;
const int maxn(1e5 + 10);
const int maxm(2e5 + 10);
int pos[10];
char s[maxn];
int ecnt, head[maxn];
int tim, dfn[maxn], low[maxn];
int scnt, id[maxn];
bool vis[maxn];
stack<int> st;

struct edge {
    int to, nxt;
} edges[maxm];

struct opt {
    int x, y;
    char a, b;
} op[maxm];

template<typename T = int>
inline const T read()
{
    T x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        x = (x << 3) + (x << 1) + ch - '0';
        ch = getchar();
    }
    return x * f;
}

template<typename T>
inline void write(T x, bool ln)
{
    if (x < 0) {
        putchar('-');
        x = -x;
    }
    if (x > 9) write(x / 10, false);
    putchar(x % 10 + '0');
    if (ln) putchar(10);
}

inline void addEdge(int u, int v)
{
    edges[ecnt].to = v;
    edges[ecnt].nxt = head[u];
    head[u] = ecnt++;
}

inline int getId(int x, char b, bool t, int n)
{
    int a = s[x] - 'a';
    b -= 'A';
    if (((a + 1) % 3 not_eq b) ^ t) {
        return x + n;
    }
    return x;
}

inline char getCh(int x, int t)
{
    int y = s[x] - 'a';
    return 'A' + ((y + t) % 3);
}

void tarjan(int u)
{
    dfn[u] = low[u] = ++tim;
    st.push(u);
    vis[u] = true;
    for (int i = head[u]; compl i; i = edges[i].nxt) {
        int v = edges[i].to;
        if (not dfn[v]) {
            tarjan(v);
            low[u] = min(low[u], low[v]);
        } else if (vis[v]) {
            low[u] = min(low[u], dfn[v]);
        }
    }
    if (dfn[u] == low[u]) {
        ++scnt;
        int v = -1;
        do {
            v = st.top();
            st.pop();
            vis[v] = false;
            id[v] = scnt;
        } while (u not_eq v);
    }
}

bool judge(int n, int m)
{
    memset(head, -1, sizeof head);
    memset(dfn, 0, sizeof dfn);
    tim = scnt = ecnt = 0;
    for (int i = 0; i < m; ++i) {
        int x = op[i].x - 1, y = op[i].y - 1;
        char a = op[i].a, b = op[i].b;
        if (s[x] not_eq a + 32) {
            if (s[y] not_eq b + 32) {
                addEdge(getId(x, a, false, n), getId(y, b, false, n));
                addEdge(getId(y, b, true, n), getId(x, a, true, n));
            } else {
                addEdge(getId(x, a, false, n), getId(x, a, true, n));
            }
        }
    }
    for (int i = 0; i < n * 2; ++i) {
        if (not dfn[i]) {
            tarjan(i);
        }
    }
    for (int i = 0; i < n; ++i) {
        if (id[i] == id[i + n]) {
            return false;
        }
    }
    return true;
}

int main()
{
#ifdef ONLINE_JUDGE
#else
    freopen("input.txt", "r", stdin);
#endif
    int n = read(), d = read();
    scanf("%s", s);
    for (int i = 0, j = 0; i < n; ++i) {
        if (s[i] == 'x') {
            pos[j++] = i;
        }
    }
    int m = read();
    for (int i = 0; i < m; ++i) {
        scanf("%d %c %d %c", &op[i].x, &op[i].a, &op[i].y, &op[i].b);
    }
    bool flag = false;
    for (int i = 0; i < (1 << d); ++i) {
        for (int j = 0; j < d; ++j) {
            if ((i >> j) & 1) {
                s[pos[j]] = 'a';
            } else {
                s[pos[j]] = 'b';
            }
        }
        if (judge(n, m)) {
            flag = true;
            break;
        }
    }
    if (not flag) {
        puts("-1");
    } else {
        for (int i = 0; i < n; ++i) {
            if (id[i] < id[i + n]) {
                putchar(getCh(i, 1));
            } else {
                putchar(getCh(i, 2));
            }
        }
        putchar(10);
    }
    return 0;
}

标签：ch,洛谷,int,++,NOI2017,low,dfn,P3825,op
来源： https://www.cnblogs.com/singularity2u/p/13992909.html