贪心，先是交换俩俩交换后就可以的，接着交换3个轮回的，每个3个轮回的要交换2次
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/*
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ID: yingzho1
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LANG: C++
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TASK: sort3
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*/
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#include <iostream>
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#include <fstream>
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#include <
string
>
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#include <map>
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#include <vector>
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#include <
set
>
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#include <algorithm>
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#include <stdio.h>
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#include <queue>
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#include <cstring>
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using
namespace
std;
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ifstream fin(
"
sort3.in
"
);
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ofstream fout(
"
sort3.out
"
);
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int
N;
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int
main()
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{
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fin >>
N;
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vector<
int
>
f(N), g(N);
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for
(
int
i =
0
; i < N; i++) fin >>
f[i];
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g =
f;
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sort(g.begin(), g.end());
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int
acount =
0
;
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for
(
int
i =
0
; i < N-
1
; i++
) {
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for
(
int
j = i+
1
; j < N; j++
) {
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if
(f[j] != g[j] && f[i] == g[j] && f[j] ==
g[i]) {
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swap(f[i], f[j]);
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acount++
;
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}
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}
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}
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int
count2 =
0
;
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for
(
int
i =
0
; i < N; i++
) {
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if
(f[i] != g[i]) count2++
;
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}
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fout << acount + count2/
3
*
2
<<
endl;
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return
0
;
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}
