CodeForces 733B Parade

枚举。枚举交换哪一个即可。

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<ctime>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0);
void File()
{
    freopen("D:\\in.txt","r",stdin);
    freopen("D:\\out.txt","w",stdout);
}
template <class T>
inline void read(T &x)
{
    char c = getchar();
    x = 0;
    while(!isdigit(c)) c = getchar();
    while(isdigit(c))
    {
        x = x * 10 + c - ‘0‘;
        c = getchar();
    }
}

int n;
int L[100010],R[100010];
int sumL,sumR;
int ans,idx;

int main()
{
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>L[i]>>R[i];
        sumL=sumL+L[i];
        sumR=sumR+R[i];
    }

    ans=abs(sumR-sumL);
    for(int i=1;i<=n;i++)
    {
        sumL=sumL-L[i];
        sumR=sumR-R[i];
        sumL=sumL+R[i];
        sumR=sumR+L[i];

        if(abs(sumR-sumL)>ans)
        {
            ans=abs(sumR-sumL);
            idx=i;
        }

        sumL=sumL-R[i];
        sumR=sumR-L[i];
        sumL=sumL+L[i];
        sumR=sumR+R[i];
    }

    cout<<idx<<endl;

    return 0;
}