差分模版题(需理解才明白)AT2442 フェーン現象 (Foehn Phenomena)
https://www.luogu.org/problemnew/show/AT2442
1 #include <bits/stdc++.h> 2 #define read read() 3 #define up(i,l,r) for(register int i = (l);i <= (r);i++) 4 #define down(i,l,r) for(register int i = (l);i >= (r);i--) 5 #define traversal_vedge(i) for(register int i = head[u]; i ;i = e[i].nxt) 6 #define ll long long 7 using namespace std; 8 int read 9 { 10 int x = 0, f = 1; char ch = getchar(); 11 while(ch < 48 || ch > 57) {if(ch == '-')f = -1; ch = getchar();} 12 while(ch >=48 && ch <=57) {x = 10 * x + ch - 48;ch = getchar();} 13 return x * f; 14 } 15 const int N = 2e5+7; 16 ll n,q,S,T,b[N],ans; 17 18 inline ll get(ll x) 19 { 20 return x > 0 ? (-x*S) : (-x*T); 21 } 22 23 int main() 24 { 25 freopen("input.txt","r",stdin); 26 n = read; q = read; S = read; T = read; 27 ll last = read; 28 up(i,1,n) 29 { 30 ll x = read; 31 b[i] = x - last; 32 last = x; 33 ans += get(b[i]); 34 } 35 //ans代表b[i](1~n)遍历后的答案; 36 while(q--) 37 { 38 int l = read, r = read, x = read; 39 ans -= get(b[l]);// b[l]改变,先减后加; 40 b[l] += x; 41 ans += get(b[l]); 42 if(r < n) 43 { 44 ans -= get(b[r+1]);//debug -= -> += 45 b[r+1] -= x; 46 ans += get(b[r+1]);//degug += -> -= 47 } 48 printf("%lld\n",ans); 49 } 50 return 0; 51 }
