Codeforces Round # 555 (Div. 3) C2. Increasing subsequence (complicated version) (贪心)

题目链接：http://codeforces.com/contest/1157/problem/C2

当左右两边数字相同时，需要判断一下取哪边能得到更长的递增序列

#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <queue>
#include <climits>
#include <set>
#include <stack>
#include <string>
#include <map>
#include <vector>
#define INF 0x3f3f3f3f
using namespace std;
typedef long long ll;
static const int MAX_N = 2e5 + 5;
static const ll Mod = 2009;
char str[MAX_N];
int a[MAX_N];
void solve(){
//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stdout);int n;while(scanf("%d", &n) != EOF){for(int i = 0; i < n; ++i) scanf("%d", &a[i]);int s = 0, e = n - 1, cnt = 0, prev = 0;   //prev为序列中最大值while(s <= e){if(a[s] <= prev){while(a[e] > prev && e >= s){prev = a[e--];str[cnt++] = 'R';}break;}if(a[e] <= prev){while(a[s] > prev && s <= e){prev = a[s++];str[cnt++] = 'L';}break;}if(a[s] < a[e] && a[s] > prev){prev = a[s++];str[cnt++] = 'L';continue;}if(a[s] > a[e] && a[e] > prev){prev = a[e--];str[cnt++] = 'R';continue;}int e1 = 0, e2 = 0;if(a[s] > prev){e1 = 1;while(s + e1 <= e && a[s + e1] > a[s + e1 - 1]) ++e1;}if(a[e] > prev){e2 = 1;while(e - e2 >= s && a[e - e2] > a[e - e2 + 1]) ++e2;}if(e1 > e2){prev = a[s++];str[cnt++] = 'L';}else{prev = a[e--];str[cnt++] = 'R';}}str[cnt] = '\0';printf("%d\n%s\n", cnt, str);}
}
int main() {solve();return 0;
}

View Code

转载于:https://www.cnblogs.com/xorxor/p/10959984.html

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