PAT第三天

1005 Spell It Right

1.以下代码有两个错误提交，考虑到可能是整形溢出

#include<iostream>
#include<cstring>
using namespace std;

int main(){
    int n;cin>>n;
    int sum=0;
    while(n){
        sum +=n%10;
        n=n/10;
    }
    string cur[10]={"zero","one","two","three","four","five","six","seven","eight","nine"};
    int k=0;
   
    string ans="";
     k=sum%10;
    ans +=cur[k];
    while(sum/10){
        ans =" "+ans;
        sum /=10;
        k=sum%10;
        ans =cur[k]+ans;
    }
    cout<<ans;
    return 0;
}

2.正确做法

#include<iostream>
#include<cctype>
using namespace std;
string cur[10]={"zero","one","two","three","four","five","six","seven","eight","nine"};
int main(){
    int sum=0;
    char c;
    while(isdigit(c=getchar())){
        sum+=c-'0';
    }
    string temp=to_string(sum);
    
    for(int i=0;i<temp.size();i++){
        if(i)cout<<' ';
        cout<<cur[temp[i]-'0'];
    }
    return 0;
}

1006 Sign In and Sign Out

#include <iostream>
#include <climits>
using namespace std;
int main() {
    int n, minn = INT_MAX, maxn = INT_MIN;
    scanf("%d", &n);
    string unlocked, locked;
    for(int i = 0; i < n; i++) {
        string t;
        cin >> t;
        int h1, m1, s1, h2, m2, s2;
        scanf("%d:%d:%d %d:%d:%d", &h1, &m1, &s1, &h2, &m2, &s2);
        int tempIn = h1 * 3600 + m1 * 60 + s1;
        int tempOut = h2 * 3600 + m2 * 60 + s2;
        if (tempIn < minn) {
            minn = tempIn;
            unlocked = t;
        }
        if (tempOut > maxn) {
            maxn = tempOut;
            locked = t;
        }
    }
    cout << unlocked << " " << locked;
    return 0;
}

1007 Maximum Subsequence Sum

解题思路：利用前缀和+双指针

#include<iostream>
#include<algorithm>
using namespace std;

int main(){
    int n;cin>>n;
    int dp[n],dp2[n],sum=-1,first=0,second=0,low=0;
    for(int i=0;i<n;i++){
        cin>>dp[i];
        if(!i){
             dp2[i]=dp[i];
        }
        else{
            dp2[i]=dp2[i-1]+dp[i]; 
        }
    }
    if(n==1){
        sum=dp[0];
        first=dp[0];
        second=dp[0];
    }
    else{
            for(int end=1;end<n;end++){
                if(dp2[end]-dp2[low]>sum){
                    sum=dp2[end]-dp2[low];
                    first=dp[low+1];
                    second=dp[end];
                }
                if(dp2[low]>dp2[end])low=end;
             }
    }

    if(sum<0)cout<<0<<' '<<dp[0]<<' '<<dp[n-1];
    else cout<<sum<<' '<<first<<' '<<second;
    return 0;
}