“玲珑杯”ACM比赛 Round #4 E -- array DP

http://www.ifrog.cc/acm/problem/1050?contest=1006&no=4

DP[val]表示以val这个值结尾的等差数列有多少个

DP[val] += DP[val / 2];

数值很大，用map<int, int>DP即可。

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#define IOS ios::sync_with_stdio(false)
using namespace std;
#define inf (0x3f3f3f3f)
typedef long long int LL;

#include <iostream>
#include <sstream>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <string>
const int maxn = 1e5 + 20;
set<int>ss;
map<int, int>dp;
const int MOD = 1e9 + 7;
void work() {
    ss.clear();
    dp.clear();
    int n;
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        int x;
        cin >> x;
        if (x == 1) {
            ss.insert(x);
            dp[1]++;
        } else {
            if (x & 1) continue;
            ss.insert(x);
            dp[x] += dp[x / 2];
            dp[x] %= MOD;
        }
    }
    int ans = 0;
    for (set<int> :: iterator it = ss.begin(); it != ss.end(); ++it) {
        int t = *it;
        if (t == 1) {
            ans += dp[t];
            ans %= MOD;
        } else {
            if (t & 1) continue;
            ans += dp[t];
            ans %= MOD;
        }
    }
    cout << ans << endl;
}

int main() {
#ifdef local
    freopen("data.txt","r",stdin);
#endif
    IOS;
    int t;
    cin >> t;
    while (t--) work();
    return 0;
}