T2：中间值（median）———2019.10.15

代码：

 #include <bits/stdc++.h>

 int ri() {
     char c = getchar(); int x = , f = ; for(;c < '' || c > ''; c = getchar()) if(c == '-') f = -;
     for(;c >= '' && c <= ''; c = getchar()) x = (x << ) + (x << ) - '' + c; return x * f;
 }
 const int N = 5e5+;

 int a[N], b[N];

 int kth(int ta[], int sa, int tb[], int sb, int k) {
     if (sa > sb) return kth(tb, sb, ta, sa, k);
     if (sa == ) return tb[k];
     if (k == ) return std::min(ta[], tb[]);
     int ka = std::min(sa, k/), kb = k - ka;
     if (ta[ka] < tb[kb]) return kth(ta+ka, sa-ka, tb, sb, k-ka);
     return kth(ta, sa, tb+kb, sb-kb, k-kb);
 }

 int query(int la, int ra, int lb, int rb) {
     int sa = ra-la+, sb = rb-lb+, siz = sa + sb;
     return kth(a+la-, sa, b+lb-, sb, siz/+);
 }

 int main() {
     freopen("median.in", "r", stdin);
     freopen("median.out", "w", stdout);
     int n, m;
     n = ri(); m = ri();
     for (int i = ; i <= n; i++) a[i] = ri();
     for (int i = ; i <= n; i++) b[i] = ri();
     for (int opt; m--; ) {
         opt = ri();
         if (opt == ) {
             int la = ri(), ra = ri(), lb = ri(), rb = ri();
             printf("%d\n", query(la, ra, lb, rb));
         } else {
             int p = ri(), pos = ri(), val = ri();
             if (p == ) a[pos] = val;
             else b[pos] = val;
         }
     }
     return ;
 }
 /*
 5 5
 12 41 46 68 69
 35 61 82 84 96
 2 1 4 3 5
 1 0 5 75
 2 2 4 3 4
 2 3 4 1 5
 2 1 4 2 4
 */