基础01背包问题

http://www.51nod.com/onlineJudge/questionCode.html#!problemId=1085

http://hihocoder.com/problemset/problem/1038?sid=320857

在N件物品取出若干件放在容量为W的背包里，每件物品的体积为W1，W2……Wn（Wi为整数），与之相对应的价值为P1,P2……Pn（Pi为整数）。求背包能够容纳的最大价值。

动态转移方程    dp[i][j]=max(dp[i-1][j],dp[i-1][j-v[i]]+w[i]);

背包九讲里面讲的很好。

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cmath>
 4 #include <vector>
 5 #include <cstring>
 6 #include <string>
 7 #include <algorithm>
 8 #include <string>
 9 #include <set>
10 #include <functional>
11 #include <numeric>
12 #include <sstream>
13 #include <stack>
14 #include <map>
15 #include <queue>
16
17 #define CL(arr, val)    memset(arr, val, sizeof(arr))
18
19 #define ll long long
20 #define inf 0x7f7f7f7f
21 #define lc l,m,rt<<1
22 #define rc m + 1,r,rt<<1|1
23 #define pi acos(-1.0)
24
25 #define L(x)    (x) << 1
26 #define R(x)    (x) << 1 | 1
27 #define MID(l, r)   (l + r) >> 1
28 #define Min(x, y)   (x) < (y) ? (x) : (y)
29 #define Max(x, y)   (x) < (y) ? (y) : (x)
30 #define E(x)        (1 << (x))
31 #define iabs(x)     (x) < 0 ? -(x) : (x)
32 #define OUT(x)  printf("%I64d\n", x)
33 #define lowbit(x)   (x)&(-x)
34 #define Read()  freopen("a.txt", "r", stdin)
35 #define Write() freopen("b.txt", "w", stdout);
36 #define maxn 1000000000
37 #define N 100010
38 using namespace std;
39
40 int n,m;
41 int f[N];
42 void ZeroOnePack(int cost,int weight)
43 {
44     for(int v=m;v>=cost;v--)
45         f[v]=max(f[v],f[v-cost]+weight);
46 }
47 int main()
48 {
49    //Read();
50    //Write();
51    int a,b;
52     while(~scanf("%d%d",&n,&m))
53     {
54         memset(f,0,sizeof(f));
55         for(int i=0;i<n;i++)
56         {
57             scanf("%d%d",&a,&b);
58             ZeroOnePack(a,b);
59         }
60         printf("%d\n",f[m]);
61     }
62     return 0;
63 }