洛谷 P5016 龙虎斗（模拟）

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cmath>
 4 
 5 using namespace std;
 6 
 7 long long n, p1, s1, s2, sum1, sum2, ans = 1e19, m, now, t1, t2, tmp;
 8 long long c[10000005];
 9 
10 int main(){
11     scanf("%lld", &n);
12     for(int i = 1; i <= n; i++) scanf("%lld", &c[i]);
13     scanf("%lld%lld%lld%lld", &m, &p1, &s1, &s2);
14     c[p1] += s1;
15     for(int i = 1; i <= m - 1; i++) sum1 += c[i] * (m - i);
16     for(int i = m + 1; i <= n; i++) sum2 += c[i] * (i - m);
17     if(sum1 == sum2) {printf("%lld", m); return 0;}
18     for(int i = 1; i <= n; i++){
19         t1 = sum1, t2 = sum2;
20         if(i < m) t1 += (m - i) * s2;
21         else t2 += (i - m) * s2;
22         tmp = abs(t1 - t2); 
23         if(tmp < ans) {ans = tmp; now = i;}
24     }
25     printf("%lld", now);
26     return 0;
27 }