AtCoder Beginner Contest 072

这应该是我第二次打AtCoder, 题目其实并不难,就是自己经验不足想复杂了,再加上自己很笨,愣是做了97分钟才全做出来(最后三分钟,有点小激动。。),看着前面大牛半个小时都搞完了,真心膜拜一下,代码其实没什么可看的,题目也没什么可说的,就是为了贴出来总结经验,下次再战!

链接:http://abc072.contest.atcoder.jp/

A:直接做就可以了

#include<bits/stdc++.h>

using namespace std;
const int INF = (1 << 30);
const int N = 100000 + 5;
const double eps = 1e-8;
const int M = 100 + 5;
const int MOD = 1e9;

char str[N];
int main(){
    int x, t;
    scanf("%d %d", &x, &t);
    printf("%d\n", max(x - t, 0));
}

 

B:也是直接做就可以了

#include<bits/stdc++.h>

using namespace std;
const int INF = (1 << 30);
const int N = 100000 + 5;
const double eps = 1e-8;
const int M = 100 + 5;
const int MOD = 1e9;

char str[N];
int main(){
    scanf("%s", str);
    int len = strlen(str);
    for(int i = 0; i < len; i += 2) putchar(str[i]);
    puts("");
}

 

C:只要考虑a[i+1] + a[i] + a[i+2]就可以了

#include<bits/stdc++.h>

using namespace std;
const int INF = (1 << 30);
const int N = 100000 + 5;
const double eps = 1e-8;
const int M = 100 + 5;
const int MOD = 1e9;

int a[N];
int main(){
    int n, ans = 0, x, maxn = 0;
    scanf("%d", &n);
    for(int i = 1; i <= n; i++){
        scanf("%d", &x); ++ a[x];
        if(x > maxn) maxn = x;
    }
    for(int i = 0; i <= maxn; i++)
        ans = max(ans, a[i] + a[i + 1] + a[i + 2]);
    printf("%d\n", ans);
}

 

D:没想到这么直接,直接swap就行了,我以为有什么套路结果卡着半天,最后还剩3分钟的时候直接交上去竟然AC了。。。神奇。。。

#include<bits/stdc++.h>

using namespace std;
const int INF = (1 << 30);
const int N = 100000 + 5;
const double eps = 1e-8;
const int M = 100 + 5;
const int MOD = 1e9;

int a[N];
int main(){
    int n, ans = 0;
    scanf("%d", &n);
    for(int i = 1; i <= n; i++) scanf("%d", &a[i]);

    for(int i = 1; i < n; i++)
        if(a[i] == i) swap(a[i], a[i + 1]), ans++;
    if(a[n] == n) ans++;
    printf("%d\n", ans);
}

 

posted @ 2017-09-02 22:37  Pretty9  阅读(134)  评论(0编辑  收藏  举报