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  • Subsequence(二分)

    A sequence of N positive integers (10 < N < 100 000), each of them less than or equal 10000, and a positive integer S (S < 100 000 000) are given. Write a program to find the minimal length of the subsequence of consecutive elements of the sequence, the sum of which is greater than or equal to S.

    Input

    The first line is the number of test cases. For each test case the program has to read the numbers N and S, separated by an interval, from the first line. The numbers of the sequence are given in the second line of the test case, separated by intervals. The input will finish with the end of file.

    Output

    For each the case the program has to print the result on separate line of the output file.if no answer, print 0.

    Sample Input

    2
    10 15
    5 1 3 5 10 7 4 9 2 8
    5 11
    1 2 3 4 5

    Sample Output

    2
    3

    一开始c++交不过,g++过,原来是int 输入的时候是long long,wa了,g++交没这个问题

    代码:

    #include<cstdio>
    #include<iostream>
    #include<algorithm>
    #include<cstring>
    #include<map>
    #include<set>
    #include<stack>
    #include<queue>
    #include<cmath>
    
    const int maxn=1e5+5;
    typedef long long ll;
    using namespace std;
    ll a[maxn];
    ll s[maxn];
    ll n,ss;
    bool check(int x)
    {
        if(x>=n)
        {
        	return true;
    	}
    	for(int t=x;t<=n;t++)
    	{
    //		cout<<s[t]<<" "<<s[t-x+1]<<endl;
    		if(s[t]-s[t-x+1]>=ss)
    		{
    			
    			return true;
    		}
    	}
    	return false;
    }
    int  main()
    {
    	int  T;
    	cin>>T;
    	while(T--)
    	{
    		scanf("%lld%lld",&n,&ss);
    		for(int t=1;t<=n;t++)
    		{
    			scanf("%lld",&a[t]);
    		}
    		memset(s,0,sizeof(s));
    		for(int t=1;t<=n;t++)
    		{
    			s[t]=s[t-1]+a[t];
    		}
    		if(s[n]<ss)
    		{
    			cout<<"0"<<endl;
    	    }
    	    else
    	    {
    		int l=0,r=100000;
    		int mid;
    		while(l<=r)
    		{
    			mid=(l+r)/2;
    			if(check(mid))
    			{
    		      r=mid-1;
    			}
    			else
    			{
    			  l=mid+1;
    			}
    		}
    		mid=(l+r)/2;
    		cout<<mid<<endl;
    	   }
    	}
    	
    	return 0;
    }
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  • 原文地址:https://www.cnblogs.com/Staceyacm/p/10781772.html
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