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| #include <bits/stdc++.h>
const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;
#define LL long long
#define f(i, a, b) for (int i = a; i <= b; i++)
#define IN freopen("in.txt", "r", stdin)
#define OUT freopen("out.txt", "w", stdout)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define sqr(x) (x) * (x)
#define pr1(x) printf("Case %d: ", x)
#define pn1(x) printf("Case %d:\n", x)
#define pr2(x) printf("Case #%d: ", x)
#define pn2(x) printf("Case #%d:\n", x)
#define lowbit(x) (x & (-x))
#define fi first
#define se second
typedef unsigned long long ull;
struct FastIO
{
static const int S = 5 << 20;
int wpos;
char wbuf[S];
FastIO() : wpos(0) {}
inline int xchar()
{
static char buf[S];
static int len = 0, pos = 0;
if (pos == len)
pos = 0, len = fread(buf, 1, S, stdin);
if (pos == len)
return -1;
return buf[pos++];
}
inline int xuint()
{
int c = xchar(), x = 0;
while (~c && c <= 32)
c = xchar();
for (; '0' <= c && c <= '9'; c = xchar())
x = x * 10 + c - '0';
return x;
}
inline LL xull()
{
int c = xchar();
LL x = 0;
while (~c && c <= 32)
c = xchar();
for (; '0' <= c && c <= '9'; c = xchar())
x = x * 10 + c - '0';
return x;
}
inline int xint()
{
int s = 1, c = xchar(), x = 0;
while (c <= 32)
c = xchar();
if (c == '-')
s = -1, c = xchar();
for (; '0' <= c && c <= '9'; c = xchar())
x = x * 10 + c - '0';
return x * s;
}
inline void xstring(char *s)
{
int c = xchar();
while (c <= 32)
c = xchar();
for (; c > 32; c = xchar())
*s++ = c;
*s = 0;
}
inline void wchar(int x)
{
if (wpos == S)
fwrite(wbuf, 1, S, stdout), wpos = 0;
wbuf[wpos++] = x;
}
inline void wll(LL x)
{
if (x < 0)
wchar('-'), x = -x;
char s[30];
int n = 0;
while (x || !n)
s[n++] = '0' + x % 10, x /= 10;
while (n--)
wchar(s[n]);
}
inline void wstring(const char *s)
{
while (*s)
wchar(*s++);
}
~FastIO()
{
if (wpos)
fwrite(wbuf, 1, wpos, stdout), wpos = 0;
}
} io;
LL left[100086], right[100086], leftc[100086], rightc[100086], res = 0, cntl = 2, cntr = 1, fz = 1;
int x, last, now;
int main()
{
IN;
OUT;
x = io.xuint();
last = io.xuint();
left[1] = 1;
leftc[1] = last - 1;
res += last - 1;
f(i, 2, x)
{
now = io.xuint();
if (now > last)
{
res += now - last;
left[cntl] = i;
leftc[cntl++] = now - last;
}
if (now < last)
{
right[cntr] = i;
rightc[cntr++] = last - now;
}
last = now;
}
io.wll(res);
f(i, 1, cntl - 1)
{
while (leftc[i]--)
{
io.wchar('\n');
io.wll(left[i]);
io.wchar(' ');
if (rightc[fz] > 0)
{
io.wll(right[fz] - 1);
rightc[fz] -= 1;
if (rightc[fz] == 0)
fz += 1;
}
else
io.wll(x);
}
}
return 0;
}
|
