some easy algorithm

Search/1-sherlock-and-array.cpp

@@ -0,0 +1,41 @@
+#include <iostream>
+#include <cstdio>
+
+using namespace std;
+
+int main(int argc, char const *argv[])
+{
+    int T;
+    cin >> T;
+    while (T --) {
+        int N;
+        cin >> N;
+        int A[N];
+        int sum = 0;
+        for (int i = 0; i < N; i ++) {
+            scanf("%d", &A[i]);
+            sum += A[i];
+        }
+
+        int right = sum;
+        bool exists = false;
+
+        for (int i = 0; i < N; i ++) {
+            int left = sum - right;
+            right -= A[i];
+
+            if (left == right) {
+                exists = true;
+                break;
+            }
+        }
+
+        if (exists) {
+            cout << "YES" << endl;
+        } else {
+            cout << "NO" << endl;
+        }
+    }
+
+    return 0;
+}

Search/1-sherlock-and-array.php

@@ -0,0 +1,31 @@
+<?php
+
+$handle = fopen("php://stdin", "r");
+fscanf($handle, "%d", $t);
+
+while ($t --) {
+    fscanf($handle, "%d", $n);
+    $arr = array_map('intval', explode(' ', trim(fgets($handle))));
+
+    if ($n == 1) {
+        echo "YES\n";
+        continue;
+    }
+
+    $exists = false;
+
+    $sum = array_sum($arr);
+    $right = $sum;
+
+    for ($i=0; $i < $n; $i++) {
+        $left = $sum - $right;
+        $right = $right - $arr[$i];
+
+        if ($left == $right) {
+            $exists = true;
+            break;
+        }
+    }
+
+    echo $exists ? "YES\n" : "NO\n";
+}

Search/2-icecream-parlor.php

@@ -0,0 +1,22 @@
+<?php
+
+$handle = fopen("php://stdin", "r");
+fscanf($handle, "%d", $T);
+
+while ($T --) {
+    fscanf($handle, "%d", $M);
+    fscanf($handle, "%d", $N);
+    $prices = array_map('intval', explode(' ', trim(fgets($handle))));
+
+    $searched = [];
+    for ($i=0; $i < $N; $i++) {
+        $diff = $M - $prices[$i];
+
+        if (array_key_exists($diff, $searched)) {
+            printf("%d %d\n", $searched[$diff] + 1, $i + 1);
+            break;
+        }
+
+        $searched[$prices[$i]] = $i;
+    }
+}

Search/3-maximise-sum.cpp

@@ -0,0 +1,51 @@
+#include <cstdio>
+#include <vector>
+#include <set>
+
+using namespace std;
+
+typedef unsigned long long ull;
+
+ull find_result(const vector<ull> &v, ull m) {
+    vector<ull> prefix;
+    set<ull> s;
+
+    // get prefix array
+    size_t v_size = v.size();
+    ull tmp = 0;
+    for (size_t i=0; i<v_size; ++i) {
+        tmp += v[i];
+        tmp %= m;
+        prefix.push_back(tmp);
+    }
+
+    ull res = 0;
+    for (size_t i=0; i<v_size; ++i) {
+        auto it = s.upper_bound(prefix[i]);
+        if (it != s.end()) {
+            tmp = (prefix[i] - *it + m) % m;
+            res = max(res, tmp);
+        }
+        s.insert(prefix[i]);
+        res = max(res, prefix[i]);
+    }
+    return res;
+}
+
+int main()
+{
+    int cnt;
+    scanf("%d", &cnt);
+    vector<ull> v;
+    ull n, m, tmp;
+    for (int i=0; i<cnt; ++i) {
+        scanf("%llu %llu", &n, &m);
+        v.clear();
+        for (int j=0; j<n; ++j) {
+            scanf("%llu", &tmp);
+            v.push_back(tmp);
+        }
+        printf("%llu\n", find_result(v, m));
+    }
+    return 0;
+}

Search/3-maximise-sum.php

@@ -0,0 +1,42 @@
+<?php
+
+$T = trim(fgets(STDIN));
+
+while ($T --) {
+    fscanf(STDIN, "%d %d", $n, $m);
+    $nums = array_map('intval', explode(' ', trim(fgets(STDIN))));
+
+    $psum = array(-1 => 0);
+    $msum = array(-1 => 0);
+    $midx = array();
+    $midx[0][] = -1;
+    $max = 0;
+    for ($i=0; $i < $n; $i++) {
+        $psum[$i] = $psum[$i - 1] + $nums[$i];
+        $msum[$i] = $psum[$i] % $m;
+        $midx[$msum[$i]][] = $i;
+        if ($msum[$i] > $max)
+            $max = $msum[$i];
+    }
+    // print_r($psum);
+    // print_r($msum);
+
+    sort($msum);
+    for ($i=1; $i <= $n; $i++) {
+        $sum1 = $msum[$i - 1];
+        $sum2 = $msum[$i];
+        // echo "sum1:$sum1, sum2:$sum2\n";
+        foreach ($midx[$sum1] as $p1) {
+            foreach ($midx[$sum2] as $p2) {
+                if ($p1 > $p2) {
+                    $d = $sum1 - $sum2;
+                    if ($d < 0 && $m + $d > $max) {
+                        $max = $m + $d;
+                    }
+                }
+            }
+        }
+    }
+
+    echo $max . "\n";
+}

Search/4-missing-numbers.cpp

@@ -0,0 +1,33 @@
+#include <iostream>
+#include <cstdio>
+
+typedef unsigned long ul;
+
+using namespace std;
+
+int main(int argc, char const *argv[])
+{
+    ul n, m;
+    cin >> n;
+    int times[10005] = {0};
+    for (ul i = 0; i < n; i ++) {
+        int temp;
+        scanf("%d", &temp);
+        times[temp] --;
+    }
+
+    cin >> m;
+    for (ul i = 0; i < m; i ++) {
+        int temp;
+        scanf("%d", &temp);
+        times[temp] ++;
+    }
+
+    for (int i = 0; i < 10005; i ++) {
+        if (times[i] >= 1) {
+            cout << i << " ";
+        }
+    }
+
+    return 0;
+}

Search/4-missing-numbers.php

@@ -0,0 +1,6 @@
+<?php
+
+$handle = fopen("php://stdin", "r");
+fscanf($handle, "%d", $n);
+
+var_dump($list1);

Search/5-connected-cell-in-a-grid.php

@@ -0,0 +1,12 @@
+<?php
+
+// not solve
+
+$handle = fopen("php://stdin", "r");
+fscanf($handle, "%d", $m);
+fscanf($handle, "%d", $n);
+
+while ($m --) {
+    $matrix[] = array_map('intval', explode(' ', trim(fgets($handle))));
+}
+// var_dump($matrix);