day1 飞扬的小鸟

这是一道典型的DP，f[i][j],i表示横坐标，j表示纵坐标，每一个横坐标都用完全背包来计算，其中有些特判，请在程序中体会：

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#define maxn 10010
using namespace std;
const int inf=0x7ffffff;
int n,m,k,p,l,h;
int x[maxn],y[maxn],down[maxn],up[maxn];
int f[maxn][1001];
int main() 
{
    freopen("bird.in","r",stdin);
    freopen("bird.out","w",stdout);
    scanf("%d%d%d",&n,&m,&k);
    for (int i=0;i<n;i++)
        scanf("%d%d",&x[i],&y[i]);
    for (int i=1;i<=n;i++)
    {
        down[i]=0;
        up[i]=m+1;
    }
    for(int i=1;i<=k;i++) 
    {
        cin>>p>>l>>h;
        down[p]=l;
        up[p]=h;
    }
    for (int i=1;i<=n;i++)
        for (int j=0;j<=m;j++)
                 f[i][j]=inf;
    f[0][0]=inf;
    int arrive=k;
    for (int i=1;i<=n;i++) 
    {
        for (int j = 1; j <= m; j++) 
        {
            if(j >= x[i-1])
            {
                f[i][j] = min(f[i][j], f[i-1][j-x[i-1]] + 1);
                f[i][j] = min(f[i][j], f[i][j-x[i-1]] + 1);
            }
            if(j == m) 
            {
                for(int k=j-x[i-1];k<=m;k++) 
                {
                    f[i][j] = min(f[i][j], f[i-1][k] + 1);
                    f[i][j] = min(f[i][j], f[i][k] + 1);
                }
            }
        }
        for (int j = down[i]+1; j <= up[i]-1; ++j)
            if( j + y[i-1] <= m)
                f[i][j] = min(f[i][j], f[i-1][j+y[i-1]]);
        for (int j = 1; j <= down[i]; j++) f[i][j] = inf;
        for (int j = up[i]; j <= m; j++) f[i][j] = inf;
    }
    int cnt = k, ans = inf;
    for (int i = n; i >= 1; i--) 
    {
        for (int j = down[i]+1; j <= up[i]-1; ++j)
            if (f[i][j] < inf)
               ans = min(ans, f[i][j]);
        if (ans != inf) break;
        if (up[i] <= m)
           cnt --;
    }
    if(cnt==k)
        printf("1
%d
", ans);
    else 
        printf("0
%d
", cnt);
    return 0;
}

清清正正射命丸文是也~