'commit'

TangDou/AcWing/SegmentTree/POJ3264_XDS.cpp

@@ -0,0 +1,63 @@
+#include <iostream>
+#include <algorithm>
+#include <cstdio>
+#include <cstring>
+using namespace std;
+
+const int INF = 0x3f3f3f3f;
+const int N = 50010;
+int a[N];
+
+struct Node {
+    int l, r, mx, mi;
+} tr[N << 2];
+
+int mx, mi;
+void pushup(int u) {
+    tr[u].mx = max(tr[u << 1].mx, tr[u << 1 | 1].mx);
+    tr[u].mi = min(tr[u << 1].mi, tr[u << 1 | 1].mi);
+}
+void build(int u, int l, int r) {
+    tr[u].l = l, tr[u].r = r; // POJ对于tr[u]={l,r}报编译错误，编译器版本太低，需要手动实现构造函数
+
+    if (l == r) {
+        tr[u].mx = a[l], tr[u].mi = a[l];
+        return;
+    }
+    int mid = (l + r) >> 1;
+    build(u << 1, l, mid), build(u << 1 | 1, mid + 1, r);
+    pushup(u);
+}
+
+void query(int u, int l, int r) {
+    if (l <= tr[u].l && r >= tr[u].r) {
+        mx = max(mx, tr[u].mx), mi = min(mi, tr[u].mi);
+        return;
+    }
+
+    int mid = (tr[u].l + tr[u].r) >> 1;
+
+    if (l <= mid) query(u << 1, l, r);
+    if (r > mid) query(u << 1 | 1, l, r);
+}
+
+int main() {
+#ifndef ONLINE_JUDGE
+    freopen("POJ3264.in", "r", stdin);
+#endif
+    // 加快读入
+    ios::sync_with_stdio(false), cin.tie(0);
+    int n, q;
+    cin >> n >> q;
+    for (int i = 1; i <= n; i++) cin >> a[i];
+    build(1, 1, n);
+
+    while (q--) {
+        mx = -INF, mi = INF;
+        int l, r;
+        cin >> l >> r;
+        query(1, l, r);
+        printf("%d\n", mx - mi);
+    }
+    return 0;
+}