kuangbinで飛ぶことができます[2ポイント] POJ-3258 River Hopscotch（整数2ポイント）

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#include<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
#include<algorithm>
#define ll long long
#define int ll
#define INF 0x3f3f3f3f
#define NUM 50010
using namespace std;
int a[NUM];
int L, N, M;
bool check(int x)
{
    
    
    int cnt = 0;
    int j = 0;
    for (int i = 1; i <= N; i++) {
    
    
        if (a[i] - a[j] < x) cnt++;
        else j = i;
    }
    return cnt <= M;
}
signed main()
{
    
    
    scanf("%lld%lld%lld", &L, &N, &M);
    for (int i = 1; i <= N; i++) 
        scanf("%lld", &a[i]);
    a[0] = 0;
    a[++N] = L;
    sort(a, a + (N + 1));
    int l = 0, r = INF;
    while (l < r) {
    
    
        int mid = r + l >> 1;
        if (check(mid)) 
            l = mid;
        else 
            r = mid;
    }
    printf("%lld\n", l);

}