POJ 1051 Jury Compromise ——（暴力DP）

　　题目不难，暴力地dp一下就好，但是不知道我WA在哪里了，对拍了好多的数据都没找出错误= =。估计又是哪里小细节写错了QAQ。。思路是用dp[i][j]表示已经选了i个，差值为j的最大和。转移的话暴力枚举当前选那个即可。代码如下（WA的，以后有机会再找找错在哪里吧0.0）：

#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <set>
using namespace std;
const int N = 200 + 5;

int n,m;
int a[N],b[N];
struct node
{
    int now,pre,val;
    int a,b;
}dp[20+5][800+5];

set<int> get(int x)
{
    set<int> S;
    for(int i=m;i>=1;i--)
    {
        S.insert(dp[i][x].now);
        x = dp[i][x].pre;
    }
    return S;
}

int main()
{
    int kase = 1;
    while(scanf("%d%d",&n,&m) == 2)
    {
        if(n == 0 & m == 0) break;
        for(int i=1;i<=n;i++) scanf("%d%d",a+i,b+i);
        for(int i=0;i<=800;i++) dp[0][i] = (node){-1,-1,0,0,0};
        dp[0][400] = (node){0,-1,0,0,0};
        for(int i=1;i<=m;i++)
        {
            for(int j=0;j<=800;j++)
            {
                dp[i][j] = (node){-1,-1,0,0,0};
                for(int k=1;k<=n;k++)
                {
                    int add = a[k] - b[k];
                    if(j-add < 0 || j - add > 800) continue;
                    int pre = j - add;
                    if(dp[i-1][pre].now == -1) continue;
                    int flag = 1;
                    for(int p=i-1;p>=1;p--)
                    {
                        if(dp[p][pre].now == k)
                        {
                            flag = 0;
                            break;
                        }
                        else pre = dp[p][pre].pre;
                    }
                    if(flag == 0) continue;
                    if(dp[i-1][j - add].val + a[k]+b[k] > dp[i][j].val)
                    {
                        dp[i][j] = (node){k,j-add,dp[i-1][j - add].val + a[k]+b[k],
                        dp[i-1][j - add].a + a[k], dp[i-1][j - add].b + b[k]};
                    }
                }
            }
        }
        set<int> S;
        int aa, bb;
        for(int add=0;add<=400;add++)
        {
            if(dp[m][400-add].now == -1 && dp[m][400+add].now == -1) continue;
            int temp = 0;
            if(dp[m][400-add].now != -1)
            {
                temp = dp[m][400-add].val;
                S = get(400-add);
                aa = dp[m][400-add].a, bb = dp[m][400-add].b;
            }
            if(dp[m][400+add].now != -1)
            {
                if(dp[m][400+add].val > temp)
                {
                    S = get(400+add);
                    aa = dp[m][400+add].a, bb = dp[m][400+add].b;
                }
            }
            break;
        }
        printf("Jury #%d
",kase++);
        printf("Best jury has value %d for prosecution and value %d for defence:
",aa,bb);
        for(set<int>::iterator it=S.begin();it!=S.end();it++) printf(" %d",*it);
        puts("
");
    }
    return 0;
}