The Great Mixing

这道题非常有意思

#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>
#include <vector>
#define inf 0x3f3f3f3f
using namespace std;
int a[2234];
int dp[5005];
int n, k;
int vis[5005];
vector<int>v;
int bfs() {

    int i, sum = 0;
    queue<int>q;
    for (i = 0; i < v.size(); i++) {
        int m = v[i] + 1000;
        if(vis[m]==0){
        q.push(m);
        vis[m]=1;
        dp[m] = 1;
        }
        if(m==1000) return 1;
    }
    int temp;
    while (!q.empty()) {
        temp = q.front();
        q.pop();
        for (i = 0; i < v.size(); i++) {
            sum = temp + v[i];
            if (dp[sum]>dp[temp] + 1 && sum <= 2000 && sum >= 0){
                dp[sum] = dp[temp] + 1;
            if (sum == 1000)return 1;
            if (vis[sum] == 0) {
                q.push(sum);
                vis[sum] = 1;
            }
            }
        }
    }
    return -1;
}
int main()
{
    memset(a, 0, sizeof(a));
    memset(dp, inf, sizeof(dp));
    cin >> n >> k;
    int i, t;
    for (i = 1; i <= k; i++) {
        scanf("%d",&t);
        if(a[t-n+1000]==0){
            v.push_back(t-n);
        }
        a[t-n+1000] = 1;
    }
    bfs();
    if (dp[1000] != inf)
        cout << dp[1000] << endl;
    else cout << -1 << endl;
    return 0;
}