[NOI2014]起床困难综合症

从高位往地位贪心即可

# include <bits/stdc++.h>
# define IL inline
# define RG register
# define Fill(a, b) memset(a, b, sizeof(a))
using namespace std;
typedef long long ll;
const int _(1e5 + 10);

IL ll Read(){
    RG char c = getchar(); RG ll x = 0, z = 1;
    for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1;
    for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
    return x * z;
}

int n, m, ans, t[_], op[_];

int main(RG int argc, RG char* argv[]){
    n = Read(); m = Read();
    for(RG int i = 1; i <= n; i++){
        RG char c; scanf(" %c", &c); t[i] = Read();
        if(c == 'A') op[i] = 1;
        else if(c == 'O') op[i] = 2;
        else op[i] = 3;
    }
    for(RG int l = 30; l >= 0; l--){
        RG int cnt1 = 1, cnt2 = 0;
        for(RG int i = 1; i <= n; i++){
            RG int d = (t[i] >> l) & 1;
            if(op[i] == 1) cnt1 &= d, cnt2 &= d;
            else if(op[i] == 2) cnt1 |= d, cnt2 |= d;
            else cnt1 ^= d, cnt2 ^= d;
        }
        if(cnt2) ans += 1 << l;
        else if(cnt1 && m >= (1 << l)) ans += 1 << l, m -= 1 << l;
    }
    printf("%d
", ans);
    return 0;
}