'commit'

TangDou/AcWing/BIT/POJ3264_SZSZ.cpp

@@ -0,0 +1,53 @@
+#include <algorithm>
+#include <cstdio>
+#include <cstring>
+
+const int INF = 0x3f3f3f3f;
+using namespace std;
+const int N = 50010;
+
+int a[N];
+int n, q;
+
+// 树状数组模板
+int c1[N], c2[N]; // c1:维护最大值，c2：维护最小值
+
+int lowbit(int x) {
+    return x & -x;
+}
+
+void update(int x, int d) {
+    for (int i = x; i < N; i += lowbit(i)) c1[i] = max(c1[i], d), c2[i] = min(c2[i], d);
+}
+
+int query(int x, int y) {
+    int mx = 0, mi = INF;
+    while (y >= x) {                            // 右侧到左侧
+        mx = max(mx, a[y]), mi = min(mi, a[y]); // 每次最后侧的点参加评比
+
+        for (--y; y - x >= lowbit(y); y -= lowbit(y)) // 从x~y-1检查每个片断
+            mx = max(mx, c1[y]), mi = min(mi, c2[y]);
+    }
+    return mx - mi;
+}
+
+int main() {
+#ifndef ONLINE_JUDGE
+    freopen("POJ3264.in", "r", stdin);
+#endif
+    memset(c1, 0, sizeof c1);
+    memset(c2, 0x3f, sizeof c2); // 最小值，需要先设置最大，最大值默认的就是0，不需要设置
+    scanf("%d %d", &n, &q);
+
+    for (int i = 1; i <= n; i++) {
+        scanf("%d", &a[i]);
+        update(i, a[i]);
+    }
+
+    while (q--) {
+        int a, b;
+        scanf("%d %d", &a, &b);
+        printf("%d\n", query(a, b));
+    }
+    return 0;
+}