HDU 4778 gems fight! (DP)

HDU 4778 gems fight!

Question Link

Question: There are n backpacks and some gems in the bag. Now Alice and you choose a backpack in turn, drop the jewels in the bag into the pot, and if there are gems in the pot to S, you will get the magic stone, and you can continue to choose a backpack. Both of them will follow the best strategy and ask the last two members how much the magic stone will be.

Idea: DP, DP [s] indicates the value when the status of the selected backpack is s, and then you can perform a memory-based search. Note that if the current magic stone is generated, continue to add it; otherwise, you can subtract it.

Code:

#include <stdio.h>#include <string.h>#include <algorithm>using namespace std;const int INF = 0x3f3f3f3f;const int N = 21;int g, b, s, dp[(1<<N) + 5], vis[(1<<N) + 5];int yu[(1<<N) + 5][10];struct Page {    int num;    int a[10];} p[N];int cal(int S, int u) {    int ans = 0;    for (int i = 1; i <= g; i++) {ans += (yu[S][i] + p[u].a[i]) / s;    }    return ans;}int dfs(int now) {    int &tmp = dp[now];    if (vis[now]) return tmp;    vis[now] = 1;    tmp = 0;    int Min = INF, Max = -INF;    if (now == (1<<b) - 1) return tmp;    for (int i = 0; i < b; i++) {if (now&(1<<i)) continue;int sb = cal(now, i);int next = (now|(1<<i));if (sb != 0) {    Max = max(Max, dfs(next) + sb);}else {    Min = min(Min, dfs(next));}    }    tmp = max(Max, -Min);    return tmp;}int main() {    while (~scanf("%d%d%d", &g, &b, &s) && g || b || s) {for (int i = 0; i < b; i++) {    memset(p[i].a, 0, sizeof(p[i].a));    scanf("%d", &p[i].num);    int tmp;    for (int j = 0; j < p[i].num; j++) {scanf("%d", &tmp);p[i].a[tmp]++;    }}for (int i = 0; i < (1<<b); i++) {    vis[i] = 0;    for (int j = 0; j < b; j++) {if (i&(1<<j)) continue;for (int k = 1; k <= g; k++) {    yu[i|(1<<j)][k] = (yu[i][k] + p[j].a[k]) % s;}    }}printf("%d\n", dfs(0));    }    return 0;}