[题解]luogu_P3939_数颜色（vector二分

用vector维护每种颜色出现位置，二分左右端点，右端点用upperbound，交换直接把vector里的也交换

#include<bits/stdc++.h>
#define pb push_back
using namespace std;
const int maxn=300009;
int n,m;
struct node{
    int col,w;
}a[maxn];
vector<int>c[maxn];//颜色x出现位置 
int main(){
    scanf("%d%d",&n,&m);
    for(int i=1,x;i<=n;i++){
        scanf("%d",&x);
        c[x].pb(i);
        a[i].col=x,a[i].w=c[x].size()-1;
    }
    for(int i=1,op,x,y,z;i<=m;i++){
        scanf("%d",&op);
        if(op==1){
            scanf("%d%d%d",&x,&y,&z);
            if(c[z].size()==0){
                printf("0\n");continue;
            }
            int pos1=lower_bound(c[z].begin(),c[z].end(),x)-c[z].begin();
            int pos2=upper_bound(c[z].begin(),c[z].end(),y)-c[z].begin();//查右端点用upper 
            printf("%d\n",pos2-pos1);
        }
        else{
            scanf("%d",&x);
            if(a[x].col==a[x+1].col)continue;
            c[a[x].col][a[x].w]=x+1;
            c[a[x+1].col][a[x+1].w]=x;
            swap(a[x],a[x+1]);
        }
    }
}