poj1717

两次记忆化搜索，第一次找最小的gap，第二次找最少的次数。

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int INF = 0x3f3f3f3f;
int n,x;
int a[];
int b[];
int dp[][];
int abs(int a)
{
    return a >  ? a : -a;
}
int dfs(int cur,int gap)
{
    if(dp[cur][gap] != -)
        return dp[cur][gap];
    if(cur == n)
    {
        return dp[cur][gap] = abs(gap);
    }
    int x = dfs(cur + ,gap + a[cur] - b[cur]);
    int y = dfs(cur + ,gap + b[cur] - a[cur]);
    return dp[cur][gap] = min(x, y);
}
int dfs2(int cur,int gap)
{
    if(dp[cur][gap] != -)
        return dp[cur][gap];
    if(cur == n)
    {
        if(abs(gap) == x)
            return dp[cur][gap] = ;
        return dp[cur][gap] = INF;
    }
    int p = dfs2(cur + ,gap + a[cur] - b[cur]);
    int q = dfs2(cur + ,gap + b[cur] - a[cur]) + ;
    return dp[cur][gap] = min(p, q);
}
int main()
{
    cin >> n;
    for(int i = ;i < n;i ++)
    {
        scanf("%d%d",&a[i],&b[i]);
    }
    memset(dp,-,sizeof(dp));
    x = dfs(,);
    memset(dp,-,sizeof(dp));
    cout << dfs2(,) << endl;
    return ;
}