AtCoder Beginner Contest 097

A

#include "bits/stdc++.h"
using namespace std;
const int nmax = 1e6 + 10;
const int INF = 0x3f3f3f3f;
typedef long long ll;
typedef double db;
int a,b,c,d;
int main() {
    scanf("%d %d %d %d",&a,&b,&c,&d);
    if(abs(a-b) <= d && abs(b-c) <=d ||abs(c-a) <= d ) puts("Yes");
    else puts("No");
    return 0;
}

B

#include "bits/stdc++.h"
using namespace std;
const int nmax = 1e6 + 10;
const int INF = 0x3f3f3f3f;
typedef long long ll;
typedef double db;
int x;
bool table[1005];
int pow(int x, int times){
    int ans = x;
    times --;
    while(times){
        ans *= x;
        times --;
    }
    return ans;
}
int main() {
    int m = 1;
    int tag = 0;
    table[1] = 1;
    for(int i = 2;i<=1000;++i){
        int times = 2;
        while((int)pow(i,times) <= 1000){
            table[pow(i,times)] = 1;
            times ++;
        }
    }
    scanf("%d",&x);
    for(int i = x;i>=1;--i){
        if(table[i]) {
            printf("%d\n", i);
            break;
        }
    }
    return 0;
}

C

    #include "bits/stdc++.h"
    using namespace std;
    const int nmax = 1e6 + 10;
    const int INF = 0x3f3f3f3f;
    typedef long long ll;
    typedef double db;

    int main() {
        vector<string> t;
        string s;
        int k;
        cin >> s >> k;
        for(int i=0; ifor(int j=1; j<=5; j++){
                t.push_back(s.substr(i, j));
            }
        }
        sort(t.begin(), t.end());
        unique(t.begin(), t.end());
        cout << t[k-1] << endl;
        return 0;
    }

D

    #include "bits/stdc++.h"
    using namespace std;
    const int nmax = 1e6 + 10;
    const int INF = 0x3f3f3f3f;
    typedef long long ll;
    typedef double db;
    int fa[nmax],a[nmax];
    int n,m;
    int findset(int x){
        int rt = x, temp;
        while(rt != fa[rt]) rt = fa[rt];
        while(x != rt ){
            temp = fa[x];
            fa[x] = rt;
            x = temp;
        }
        return rt;
    }
    int unionset(int x, int y){
        x = findset(x);
        y = findset(y);
        if(x == y) return -1;
        else {
            fa[x] = y;
            return 1;
        }
    }
    int main() {
        scanf("%d %d",&n,&m);
        for(int i = 1 ;i<=n; ++i) fa[i] = i;
        for(int i = 1 ;i<=n; ++i) scanf("%d",&a[i]);
        for(int i = 1 ;i<=m; ++i){
            int xx, yy;
            scanf("%d %d",&xx,&yy);
            unionset(xx, yy);
        }
        int ans  = 0;
        for(int i = 1;i<=n;++i){
            if(findset(i) == findset(a[i])) 
                ans++;
        }
        printf("%d\n", ans);
        return 0;
    }