[BZOJ入门OJ2092][Noip模拟题]舞会

#include <queue>
#include <cstdio>
using namespace std;
char buf[10000000], *ptr = buf - 1;
inline int readint(){
    int f = 1, n = 0;
    char ch = *++ptr;
    while(ch < ‘0‘ || ch > ‘9‘){
        if(ch == ‘-‘) f = -1;
        ch = *++ptr;
    }
    while(ch <= ‘9‘ && ch >= ‘0‘){
        n = (n << 1) + (n << 3) + ch - ‘0‘;
        ch = *++ptr;
    }
    return f * n;
}
const int maxn = 200000 + 10;
int N, l[maxn], r[maxn], type[maxn], val[maxn];
bool out[maxn] = {false};
struct Node{
    int a, b, v;
    Node(){}
    Node(int _a, int _b, int _v): a(_a), b(_b), v(_v){}
}t;
class cmp{
    public:
        bool operator () (const Node &x, const Node &y){
            return x.v == y.v ? x.a > y.a : x.v > y.v;
        }
};
inline int abs_(int a){
    return a >= 0 ? a : -a;
}
priority_queue<Node, vector<Node>, cmp> q;
int cnt = 0, ansa[maxn], ansb[maxn];
int main(){
    fread(buf, sizeof(char), sizeof(buf), stdin);
    N = readint();
    char tmp;
    for(int i = 1; i <= N; i++){
        tmp = *++ptr;
        while(tmp < ‘0‘ || tmp > ‘9‘) tmp = *++ptr;
        type[i] = tmp - ‘0‘;
        l[i] = i - 1;
        r[i] = i + 1;
    }
    for(int i = 1; i <= N; i++)
        val[i] = readint();
    for(int i = 1; i < N; i++)
        if(type[i] != type[i + 1])
            q.push(Node(i, i + 1, abs_(val[i] - val[i + 1])));
    while(!q.empty()){
        t = q.top(); q.pop();
        if(out[t.a] || out[t.b]) continue;
        out[t.a] = out[t.b] = true;
        cnt++;
        ansa[cnt] = t.a;
        ansb[cnt] = t.b;
        int lx = l[t.a], rx = r[t.b];
        r[lx] = rx;
        l[rx] = lx;
        if(lx != 0 && rx != N + 1 && type[lx] != type[rx]) q.push(Node(lx, rx, abs_(val[lx] - val[rx])));
    }
    printf("%d\n", cnt);
    for(int i = 1; i <= cnt; i++)
        printf("%d %d\n", ansa[i], ansb[i]);
    return 0;
}