bzoj3747 [POI2015] Kinoman

#include <stdio.h>
#include <algorithm>
using namespace std;
int f[1000010], w[1000010] , next[1000010], sign[1000010];
long long tree[4000040],add[4000040], v;
int L, R, n, m;
void update(int o, int l, int r)
{
    if (L <= l && r <= R)add[o] += v;
    else {
        int mid = (l + r) / 2;
        if (L <= mid) update(o*2, l, mid);
        if (R > mid) update(o*2+1, mid+1 , r);
    }
    tree[o] = l == r ? 0 : max(tree[o*2], tree[o*2+1]);
    tree[o] += add[o];
}

int main()
{
    //freopen("1.in", "r", stdin);
    //freopen("1.out", "w", stdout);
    scanf("%d %d", &n, &m);
    for (int i = 1; i <= n; i++)scanf("%d", &f[i]);
    for (int i = 1; i <= m; i++)scanf("%d", &w[i]);
    for (int i = n; i >= 1; i--){
        if (sign[f[i]]) next[i] = sign[f[i]];
        else next[i] = n + 1;
        sign[f[i]] = i;
    }
    for (int i = 1; i <= m; i++){
        if (sign[i])
        {
        v = (long long )w[i];L = sign[i];R = next[sign[i]] -1;
        update(1, 1, n);
        }
    }
    long long ans =0;
    for (int i = 1; i <= n; i++){
        ans = max (ans, tree[1]);
        int t = next[i];
        v = (long long ) -w[f[i]]; L = i; R = next[i] -1;
        update(1, 1, n);
        v = -v; L = R; R = next[R + 1] - 1;
        if (L <= R)
        update(1, 1, n);
    }
    printf("%lld
", ans);
}