2.2 KiB

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背包问题(一维求法)

求方案数

体积至多j

初始：f[i]=1,0<=i<=m,其余为0
01背包

   for (int j = m; j >= v; j--) f[j] += f[j - v];

完全背包

  for (int j = v; j <= m; j++) f[j] += f[j - v];

体积恰好j

初始：f[0]=1,其余为0
01背包

 for (int j = m; j >= v; j--) f[j] += f[j - v];

完全背包

 for (int j = v; j <= m; j++) f[j] += f[j - v];

体积至少j
- 初始：f[0]=1,其余为0
- 01背包
- ```
 for (int j = m; j >= 0; j--)  f[j] += f[max(0, j - v)];
```
- 完全背包代码
- 有无穷多组方案数,不这么问

求最大/小值

体积至多j

初始：f[i]=0，0 <= i <= m
01背包

 for (int j = m; j >= v; j--)  f[j] = max(f[j], f[j - v] + w);

完全背包

 for (int j = v; j <= m; j++)  f[j] = max(f[j], f[j - v] + w);

体积恰好j

求最小值

初始化f[0]=0,其它是INF
01 背包

 for (int j = m; j >= v; j--) f[j] = min(f[j], f[j - v] + w);

完全背包

for (int j = v; j <= m; j++) f[j] = min(f[j], f[j - v] + w);

求最大值

初始化f[0]=0, 其余是−INF
01背包

 for (int j = m; j >= v; j--) f[j] = max(f[j], f[j - v] + w);

完全背包

  for (int j = v; j <= m; j++) f[j] = max(f[j], f[j - v] + w);

体积至少j

求最小值

初始化f[0]=0, 其余是INF
01背包

  for (int j = m; j >= v; j--) f[j] = min(f[j], f[max(0, j - v)] + w);

完全背包

   for (int j = 0; j <= m; j++) f[j] = min(f[j], f[max(0, j - v)] + w);

求最大值
- 没有求最大值的

2.2 KiB Raw Blame History Unescape Escape

背包问题(一维求法)

求方案数

求最大/小值

2.2 KiB

Raw Blame History Unescape Escape