多重背包（二进制优化）

来源：互联网发布：海岛奇兵建筑升级数据编辑：程序博客网时间：2024/06/06 23:53

马上就要轻院校赛了，没时间了，下面是网上找的多重背包，感觉很好

void ZeroOnePack(int cost, int weight, int n) {for (int i = n; i >= cost; i--)dp[i] = max(dp[i], dp[i - cost] + weight);}void CompletePack(int cost, int weight, int n) {for (int i = cost; i <= n; i++)dp[i] = max(dp[i], dp[i - cost] + weight);}void MultiPack(int c[], int w[], int num[], int n, int m) {//c[]重量，w[]价值，n物品数，m容量，memset(dp, 0, sizeof(dp));for (int i = 1; i <= n; i++) {if (num[i] * c[i] > m)CompletePack(c[i], w[i], m);else {int k = 1;while (k < num[i]) {ZeroOnePack(k*c[i], k*w[i], m);num[i] -= k;k <<= 1;}ZeroOnePack(num[i] * c[i], num[i] * w[i], m);}}}

poj1276是一道多重背包题 by wjqin

const int maxn = 125007;int w[55], num[55];int dp[maxn];void ZeroOnePack(int c, int w, int v, int dp[]) {for (int j = c; j >= w; --j)dp[j] = max(dp[j], dp[j - w] + v);}void CompletePack(int c, int w, int v, int dp[]) {for (int j = w; j <= c; ++j)dp[j] = max(dp[j], dp[j - w] + v);}void multiPack(int n, int c, int w[], int num[], int dp[]) {fill(dp, dp + maxn, 0);for (int i = 1; i <= n; ++i) {if (num[i] * w[i] > c) {CompletePack(c, w[i], w[i], dp);}else {int k = 1;while (k < num[i]) {ZeroOnePack(c, k * w[i], k * w[i], dp);num[i] -= k;k <<= 1;}ZeroOnePack(c, num[i] * w[i], num[i] * w[i], dp);}}}

wa到不知道为啥子，memset(dp, 0,sizeof(dp));有时并未将dp数组中的值赋为0（可能与sizeof有关）, fill()更靠谱些，

big event int hdu

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