Consecutive Subsequence CodeForces - 977F

Consecutive Subsequence CodeForces - 977F

题目大意：输出一序列中给最长的连续数列的长度和与其对应的下标

分析：map<int ,int>存放最长数列的末尾值和个数，再从后往前遍历

代码：

#include<bits/stdc++.h>
using namespace std;
const int N = 200000 + 5;
map<int, int> m;
int a[N];
int res[N];
int main() {
    int n;
    scanf("%d", &n);
    int e, v;
    int ans = 0;
    for(int i = 0; i < n; i++) {
        scanf("%d", &v);
        a[i] = v; 
        m[v] = m[v-1] + 1;
        if(ans < m[v]) {
            ans = m[v];
            e = i;    
        }    
    }
    printf("%d\n", ans);
    int tot = 0;
    int flag = a[e];
    for(int i = e; i >= 0; i--) {
        if(a[i]  == flag) {
            res[tot++] = i + 1;
            flag--;
        }
        if(tot == ans) break;
    }
    for(int i = tot - 1; i > 0; i--) {
        printf("%d ", res[i]);
    }
    printf("%d\n", res[0]);
    return 0;
}