CodeForces 1004C

题目链接

https://vjudge.net/problem/CodeForces-1004C

题意

给左右机器人各一个数字p和q,左边机器人往右走,右边机器人往左走,遇到对应的数字就停下,问要使他们不相遇有多少种p,q。

思路

如果左边机器人在p位置停下,那么右边机器人q的取值是p+1到n之间不同数字的个数。

那么可以从右往左先预处理出每个位置后面不同数字的个数。

然后从左往右再跑一遍就好了。

AC代码
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<vector>
#include<set>
#include<string>
#include<sstream>
#include<cctype>
#include<map>
#include<stack>
#include<queue>
#include<list>
#include<cstdlib>
#include<ctime>
#include<utility>
using namespace std;
typedef long long ll;
const double PI=atan(1.0)*4;
const int INF = 0x3f3f3f3f;
const ll LL_INF = 0x3f3f3f3f3f3f3f3f;
const ll MOD = 1000000007;
const int maxn = 100010;

int a[maxn];    //给的数组
int b[maxn];    //b[p]表示位置p---n有多少不重复的数字
int c[maxn];    //辅助数组,记录数字c[i]是否出现过

int main()
{
//    freopen("input.txt", "r", stdin);
//    freopen("output.txt", "w", stdout);
    int n;
    scanf("%d", &n);
    for(int i = 1; i <= n; i++)
        scanf("%d", &a[i]);
    int cnt = 0;
    for(int i = n; i > 0; i--)
    {
        if(c[a[i]] == 0)
        {
            c[a[i]] = 1;
            cnt++;
        }
        b[i] = cnt;
    }
    ll ans = 0;
    memset(c, 0, sizeof(c));
    for(int i = 1; i < n; i++)
    {
        if(c[a[i]] == 0)
        {
            ans = ans + b[i + 1];
        //    printf("%d %d\n", i, b[i + 1]);
            c[a[i]] = 1;
        }
    }
    printf("%lld\n", ans);
    return 0;
}

### Codeforces Problem 1332C Explanation The provided references pertain specifically to problem 742B on Codeforces rather than problem 1332C. For an accurate understanding and solution approach for problem 1332C, it's essential to refer directly to its description and constraints. However, based on general knowledge regarding competitive programming problems found on platforms like Codeforces: Problem 1332C typically involves algorithmic challenges that require efficient data structures or algorithms such as dynamic programming, graph theory, greedy algorithms, etc., depending upon the specific nature of the task described within this particular question[^6]. To provide a detailed explanation or demonstration concerning **Codeforces problem 1332C**, one would need direct access to the exact statement associated with this challenge since different tasks demand tailored strategies addressing their unique requirements. For obtaining precise details about problem 1332C including any sample inputs/outputs along with explanations or solutions, visiting the official Codeforces website and navigating to contest number 1332 followed by examining section C is recommended. ```python # Example pseudo-code structure often seen in solving competitive coding questions. def solve_problem_1332C(input_data): # Placeholder function body; actual logic depends heavily on the specifics of problem 1332C. processed_result = process_input(input_data) final_answer = compute_solution(processed_result) return final_answer input_example = "Example Input" print(solve_problem_1332C(input_example)) ```
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