Codeforces 601B Lipshitz Sequence（高效）

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题目链接：Codeforces 601B Lipshitz Sequence

代码

#include <cstdio>#include <cstring>#include <cstdlib>#include <algorithm>using namespace std;const int maxn = 1e5 + 5;typedef long long ll;int N, M, A[maxn], L[maxn], R[maxn];int S, T[maxn], P[maxn];void init () {    scanf("%d%d", &N, &M);    for (int i = 1; i <= N; i++) scanf("%d", &A[i]);    S = 0;    for (int i = 2; i <= N; i++) {        int tmp = abs(A[i] - A[i-1]);        while (S && T[S-1] <= tmp) S--;        L[i] = S ? P[S-1] : 0;        T[S] = tmp;        P[S] = i;        S++;    }    S = 0;    for (int i = N; i > 1; i--) {        int tmp = abs(A[i] - A[i-1]);        while (S && T[S-1] < tmp) S--;        R[i] = S ? P[S-1]-1 : N;        T[S] = tmp;        P[S] = i;        S++;    }}void solve () {    int l, r;    while (M--) {        scanf("%d%d", &l, &r);        ll ans = 0;        for (int i = l + 1; i <= r; i++) {            ll tmp = abs(A[i] - A[i-1]);            ans += tmp * (i - max(l, L[i])) * (min(r, R[i]) - i + 1);        }        printf("%lld\n", ans);    }}int main () {    init();    solve();    return 0;}

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