Codeforces Round #641 (Div. 2) B

Codeforces Round #641 (Div. 2) B

dp苦手,理解万岁
–>Link

Orac and Models

  • 题意:给定长度为n的数串,求它的一个子串满足以下条件并且长度最长:
    • 值递增
    • 下标j为j-1的倍数
  • 思路:dp[i]表示以下标i为结尾的,最长的满足条件子串的长度:
    dp[i]=max(dp[i],dp[j]+1)
    因为是以倍数增长的数列详见循环:
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#pragma warning(disable:4996)
#define inf 0x3f3f3f3f
#define linf 0x3f3f3f3f3f3f3f
#define itn int
#define ll long long
#define mes(a,k) memset(a,k,sizeof(a))
//#define max(a,b) a>b?a:b
//#define min(a,b) a v[N];
void io() { ios::sync_with_stdio(false), cin.tie(0), cout.tie(0); }

int main() {
	io();
	int n;
	cin >> n;
	while (n--) {
		int len;
		cin >> len;
		for (int i = 1; i <= len; i++) {
			v[i].clear();
		}
		mes(dp, 0);
		for (int i = 1; i <= len; i++) {
			dp[i] = 1;
			cin >> a[i];
		}
		for (int i = 1; i <= len; i++) {
			for (int j = i + i; j <= len; j += i) {
				if (a[j] > a[i]) {//如果不满足就不加入v[i]
					v[i].push_back(j);
				}
			}
		}
		int maxx = 0;
		for (int i = 1; i <= len; i++) {
			for (int j : v[i]) {
				dp[j] = max(dp[j], dp[i] + 1);
			}
			maxx = max(dp[i], maxx);
		}
		cout << maxx <

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