Codeforces Round #215 (Div. 2) 解题报告

昨天第一题竟然还错了。。。真是忧伤。现在改过来了

Problem A Sereja and Coat Rack

一共有n个房间第i个能赚ai的钱不够一个房间陪d钱，算最后的赚了多少。

贪心思想赚的少的先来。

#include <iostream>
#include <cstdio>
#include <string.h>
#include <algorithm>
#define INF 0x7fffffff

using namespace std;
bool cmp(int a, int b){return a>b;}
int main()
{
//    freopen("in.txt", "r", stdin);

    int n, d, a[111], m;
    while(scanf("%d%d", &n, &d)!=EOF){
        for(int i=0; i<n; i++){
            scanf("%d", &a[i]);
        }
        scanf("%d", &m);
        int ans = 0;
        sort(a, a+n);
        for(int i=0; i<min(m,n); i++){
            ans+=a[i];
        }
        ans-=d*(m>n?(m-n):0);
        cout << ans << endl;
    }
    return 0;
}

Problem B Sereja and Suffixes
统计第i个后有多少个不同的数，开局初始化一下即可。然后每次查询。

#include <iostream>
#include <cstdio>
#include <string.h>
#include <algorithm>
#define INF 0x7fffffff

using namespace std;
int tag[100100], dp[100100], a[100100];

int main()
{
//    freopen("in.txt", "r", stdin);
    int n, m;
    while(scanf("%d%d", &n, &m)!=EOF){
        memset(tag, 0, sizeof tag);
        memset(dp, 0, sizeof dp);
        for(int i=0; i<n; i++){
            scanf("%d", &a[i]);
        }
        for(int i=n-1; i>=0; i--){
            if(tag[a[i]]==0){
                tag[a[i]] = 1;
                dp[i] = dp[i+1]+1;
            }else dp[i] = dp[i+1];
        }
        for(int i=0; i<m; i++){
            int temp;
            scanf("%d", &temp);
            cout << dp[temp-1] << endl;
        }
    }
    return 0;
}

 Problem C Sereja and Algorithm

找规律题，想了半天。最终结论很简单只要满足abs(a-b)>=2 || abs(b-c)>=2 || abs(c-a)>=2返回YES否则。

#include <iostream>
#include <cstdio>
#include <string.h>
#include <algorithm>
#define INF 0x7fffffff

using namespace std;

int dp[100100][5];
char str[100100];

bool Judge(int a, int b, int c){
    if(a==0 || b==0 || c==0) return false;
    if(abs(a-b)>=2 || abs(b-c)>=2 || abs(c-a)>=2)return false;
    return true;
}

int main()
{
//    freopen("in.txt", "r", stdin);
    while(cin >> str+1)
    {
        int len = strlen(str+1);
        for(int i=1; i<=len; i++){
            dp[i][0] = dp[i-1][0];
            dp[i][1] = dp[i-1][1];
            dp[i][2] = dp[i-1][2];
            dp[i][str[i]-'x'] ++;
        }
        int q, l, r;
        scanf("%d", &q);
        for(int i=0; i<q; i++){
            scanf("%d%d", &l, &r);
            int tx = dp[r][0]-dp[l-1][0], ty = dp[r][1]-dp[l-1][1], tz = dp[r][2]-dp[l-1][2];
            if(r-l<2)printf("YES
");
            else if(Judge(tx,ty,tz))printf("YES
");
            else printf("NO
");
        }
    }
    return 0;
}