Noip 2005 过河 - DP - 离散化

#include 
#include 
#include 
#include 
using namespace std;
#define debug(x) cerr << #x << "=" << x << endl;
const int MAXN = 10000000 + 10;
const int INF = 1<<30 - 1;
int l,s,cnt,t,m,a[MAXN],ans,dp[MAXN],b[MAXN]; 
int main() {
    cin >> l;
    cin >> s >> t >> m;
    for(int i=1; i<=m; i++) 
        cin >> a[i]; 
    if(s == t) {
        int tot = 0;
        for(int i=1; i<=m; i++) 
            if(a[i] % s == 0) 
                tot++;
        cout << tot << endl;
        return 0;
    }
    sort(a+1,a+m+1);
    for(int i=1; i<=m; i++) {
        int dis = a[i] - a[i-1];
        a[i] = a[i-1] + dis%100;
        b[a[i]] = 1;
    }
    l = (l - a[m]) % 100 + a[m];
    for(int i=1;i<=m;i++)
        b[a[i]]=1;
    memset(dp,0x3f,sizeof(dp));
    dp[0] = 0;
    for(int i=s; i<=l+t; i++) 
        for(int k=s; k<=t; k++) 
            if(i - k >= 0) 
                dp[i] = min(dp[i], dp[i-k] + b[i]);
    int ans = INF;
    for(int i=l; i<=l+t; i++) 
        ans = min(ans, dp[i]);
    cout << ans;
    return 0;
}