Fafuoj 1572 Big Castle (tree-shaped DP)

Test instructions: Given a tree, and then each time the node can be manipulated, so that the state of the node and the surrounding nodes are flipped, ask whether it can make all nodes are 1

Idea: The state of the tree-shaped DP, dp[n][2][2],

Indicates when the nth node, the value is 0 or 1, whether to flip over, the state can arrive, state transfer note the details can be
Code:

#include <cstdio> #include <cstring> #include <vector> #include <algorithm>using namespace std;    const int N = 50005;int n;int node[n];bool dp[n][2][2];void scanf_ (int &num) {char in;    BOOL Neg=false;    while ((In=getchar () > ' 9 ' | | in< ' 0 ') && in!= '-');        if (in== '-') {neg=true;    while (In=getchar ()) > ' 9 ' | | in< ' 0 ');    } num=in-' 0 ';    while (In=getchar (), in>= ' 0 ' &&in<= ' 9 ') num*=10,num+=in-' 0 '; if (neg) num=0-num;}    struct Edge {int u, v;        Edge () {} edge (int u, int v) {this->u = u;    This->v = v;    }} edge[n * 2];int en = 0;int first[n], Nex[n * 2];void add_edge (int u, int v) {Edge[en] = Edge (U, v);    Nex[en] = First[u]; First[u] = en++;}    void Dfs (int u, int p) {memset (Dp[u], false, sizeof (Dp[u]));    int odd1 = 0, oe1 = 0, even1 = 0, odd2 = 0, oe2 = 0, even2 = 0;    int sum = 0; for (int i = first[u]; i + 1; i = Nex[i]) {int v = EDGE[I].V;        if (v = = p) continue;        DFS (v, u);        if (Dp[v][0][1] && dp[v][0][0]) oe1++;        else if (dp[v][0][1]) odd1++;        else if (dp[v][0][0]) even1++;        if (Dp[v][1][1] && dp[v][1][0]) oe2++;        else if (dp[v][1][1]) odd2++;        else if (dp[v][1][0]) even2++;    sum++;        } if (Oe2 + odd2 + even2 = = sum) {if (oe2) dp[u][0][0] = dp[u][1][0] = true;            else {if (odd2&1) dp[u][!node[u]][0] = true;        else dp[u][node[u]][0] = true;        }} if (Oe1 + odd1 + even1 = = sum) {if (oe1) dp[u][0][1] = dp[u][1][1] = true;            else {if (odd1&1) dp[u][node[u]][1] = true;        else dp[u][!node[u]][1] = true;        }}}int Main () {while (~SCANF ("%d", &n)) {memset (DP, FALSE, sizeof (DP));        memset (First,-1, sizeof (first));        En = 0;        for (int i = 1; I <= n; i++) scanf_ (Node[i]);        int u, v; for (int i = 1; i <= n-1;            i++) {scanf_ (U);            Scanf_ (v);            Add_edge (U, v);        Add_edge (V, u);        } DFS (1, 0);        if (Dp[1][1][0] | | dp[1][1][1]) printf ("Great cdfpysw!\n");    else printf ("Poor nanaya!\n"); } return 0;}

Fafuoj 1572 Big Castle (tree-shaped DP)