Ultraviolet 11927-games are important (combined games + Memory)

Link to the question: Ultraviolet A 11927-games are important

A directed graph without loops is given, and the number of stones on each node is given. You can select a stone for each operation and move it to the next node. The two work in turn until they fail.

Solution: with the help of graphs, the SG value of each node is processed in a memory mode, and the NIM sum of all nodes with odd stones is obtained.

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int maxn = 1005;int N, M, g[maxn][maxn], c[maxn], s[maxn];inline int SG(int u) {    if (s[u] != -1)        return s[u];    int vis[maxn];    memset(vis, 0, sizeof(vis));    for (int i = 0; i < c[u]; i++) {        int tmp = SG(g[u][i]);        vis[tmp] = 1;    }    int ret = -1;    while (vis[++ret]);    return s[u] = ret;}void init () {    int u, v;    memset(s, -1, sizeof(s));    memset(c, 0, sizeof(c));    for (int i = 0; i < M; i++) {        scanf("%d%d", &u, &v);        g[u][c[u]++] = v;    }    for (int i = 0; i < N; i++)        s[i] = SG(i);}int main () {    while (scanf("%d%d", &N, &M) == 2 && N + M) {        init();        int ans = 0, u;        for (int i = 0; i < N; i++) {            scanf("%d", &u);            if (u&1)                ans ^= s[i];        }        printf("%s\n", ans ? "First" : "Second");    }    return 0;}