1 #include <cstdio>
  2 #include <cstring>
  3 
  4 #define MAX(a, b) (a > b ? a : b)
  5 #define MIN(a, b) (a < b ? a : b) //宏定义提高效率
  6 
  7 const int LEN = 50050;
  8 
  9 struct Seg
 10 {
 11     int left, right;
 12     int ma, mi;
 13 }seg[LEN*4];
 14 
 15 void buildt(int l, int r, int step)
 16 {
 17     seg[step].left = l;
 18     seg[step].right = r;
 19     seg[step].ma = 0;
 20     seg[step].mi = 0x7fffffff;
 21     if (l == r)
 22         return;
 23     int mid = (l + r)>>1;
 24     buildt(l, mid, step<<1);
 25     buildt(mid+1, r, step<<1|1);
 26 }
 27 
 28 void pushup(int step) //向上更新
 29 {
 30     seg[step].ma = MAX(seg[step<<1].ma, seg[step<<1|1].ma);
 31     seg[step].mi = MIN(seg[step<<1].mi, seg[step<<1|1].mi);
 32 }
 33 
 34 void update(int l, int r, int height, int step)
 35 {
 36     if (l == seg[step].left && r == seg[step].right){
 37         seg[step].mi = height;
 38         seg[step].ma = height;
 39         return;
 40     }
 41     if (seg[step].left == seg[step].right)
 42         return;
 43     int mid = (seg[step].left + seg[step].right)>>1;
 44     if (r <= mid)
 45         update(l, r, height, step<<1);
 46     else if (l > mid)
 47         update(l, r, height, step<<1|1);
 48     else{
 49         update(l, mid, height, step<<1);
 50         update(mid+1, r, height, step<<1|1);
 51     }
 52     pushup(step); //递归中更新完下一个节点后向上更新
 53 }
 54 
 55 int queryma(int l, int r, int step) //求区间最大值
 56 {
 57     if (l == seg[step].left && r == seg[step].right){
 58         return seg[step].ma;
 59     }
 60     if (seg[step].left == seg[step].right)
 61         return 0;
 62     int mid = (seg[step].left + seg[step].right)>>1;
 63     if (r <= mid)
 64         return queryma(l, r, step<<1);
 65     else if (l > mid)
 66         return queryma(l, r, step<<1|1);
 67     else{
 68         int a = queryma(l, mid, step<<1);
 69         int b = queryma(mid+1, r, step<<1|1); //防止使用宏定义时多次调用queryma，先调用得到返回值，再比较返回值
 70         return MAX(a, b);
 71     }
 72 }
 73 
 74 int querymi(int l, int r, int step) //求区间最小值
 75 {
 76     if (l == seg[step].left && r == seg[step].right){
 77         return seg[step].mi;
 78     }
 79     if (seg[step].left == seg[step].right)
 80         return 0x7fffffff;
 81     int mid = (seg[step].left + seg[step].right)>>1;
 82     if (r <= mid)
 83         return querymi(l, r, step<<1);
 84     else if (l > mid)
 85         return querymi(l, r, step<<1|1);
 86     else{
 87         int a = querymi(l, mid, step<<1);
 88         int b = querymi(mid+1, r, step<<1|1); //同上
 89         return MIN(a, b);
 90     }
 91 }
 92 
 93 int main()
 94 {
 95     int n, q;
 96     scanf("%d %d", &n, &q);
 97     buildt(1, n, 1);
 98     for(int i = 1; i <= n; i++){
 99         int t;
100         scanf("%d", &t);
101         update(i, i, t, 1);
102     }
103     for(int i = 0; i < q; i++){
104         int a, b;
105         scanf("%d %d", &a, &b);
106         printf("%d\n", queryma(a, b, 1) - querymi(a, b, 1));
107     }
108     return 0;
109 }