diff --git a/src/apple.c b/src/apple.c
index 766d543..2f5143a 100644
--- a/src/apple.c
+++ b/src/apple.c
@@ -4,14 +4,26 @@ int n;
 int k;
 int A[100000];
 
+unsigned int binary_search(int A[], int x, int n){
+  int lb = -1;
+  int ub = n;
+  while(ub - lb > 1){
+    int mid = (lb + ub) / 2;
+    if(A[mid] >= x) ub = mid;
+    else lb = mid;
+  }
+  return ub;
+}
 
 int main(){
   int i, lb, ub;
+  int ans;
   scanf("%d%d", &n, &k);
   for(i = 0; i < n; i++){
     scanf("%d", &A[i]);
   }
-
+  ans = binary_search(A, k, n);
+  printf("%d\n", ans);
 
   return 0;
 }
diff --git a/src/array.c b/src/array.c
index 13ed925..c62b61b 100644
--- a/src/array.c
+++ b/src/array.c
@@ -5,14 +5,30 @@ int k;
 int A[100000];
 
 
+unsigned int binary_search(int A[], int x, int n){
+  int lb = 0;
+  int ub = 10e8;
+  while(ub - lb > 1){
+    int bag = 0;
+    int mid = (lb + ub) / 2;
+    for(int i = 0; i < n; i++){
+      bag += (A[i]+mid-1)/mid; // bag = sum of all bags
+    }
+    if(bag <= x) ub = mid;
+    else lb = mid;
+  }
+  return ub;
+}
+
 int main(){
   int i, lb, ub;
+  int ans;
   scanf("%d%d", &n, &k);
   for(i = 0; i < n; i++){
     scanf("%d", &A[i]);
   }
-
-
+  ans = binary_search(A, k, n);
+  printf("%d\n", ans);
 
   return 0;
 }
diff --git a/src/spear.c b/src/spear.c
index 766d543..c94bfa8 100644
--- a/src/spear.c
+++ b/src/spear.c
@@ -5,13 +5,30 @@ int k;
 int A[100000];
 
 
+unsigned int binary_search(int A[], int x, int n){
+  int lb = 0;
+  int ub = 10e8;
+  while(ub - lb > 1){
+    int spear = 0;
+    int mid = (lb + ub) / 2;
+    for(int i = 0; i < n; i++){
+      spear += A[i]/mid; // spear = sum of all spears
+    }
+    if(spear >= x) lb = mid;
+    else ub = mid;
+  }
+  return lb;
+}
+
 int main(){
   int i, lb, ub;
+  int ans;
   scanf("%d%d", &n, &k);
   for(i = 0; i < n; i++){
     scanf("%d", &A[i]);
   }
-
+  ans = binary_search(A, k, n);
+  printf("%d\n", ans);
 
   return 0;
 }
diff --git a/src/works.c b/src/works.c
index 766d543..9cab15f 100644
--- a/src/works.c
+++ b/src/works.c
@@ -4,14 +4,47 @@ int n;
 int k;
 int A[100000];
 
+int check(int A[], int mid, int n, int k){
+  int times = 0;
+  int workers = 1;
+
+  for(int i = 0; i < n; i++){
+    if(A[i] > mid){ // fail to complete the job
+      return 0;
+    }
+    else if(times+A[i] <= mid){
+      times += A[i];
+    }
+    else if(A[i] <= mid){
+      times += A[i];
+      workers++;
+    }
+  }
+
+  if(workers <= k) return 1;
+  else return 0;
+}
+
+unsigned int binary_search(int A[], int x, int n){
+  int lb = 0;
+  int ub = 10e8;
+  while(ub - lb > 1){
+    int mid = (lb + ub) / 2;
+    if(check(A, mid, n, k)) ub = mid;
+    else lb = mid;
+  }
+  return ub;
+}
 
 int main(){
   int i, lb, ub;
+  int ans;
   scanf("%d%d", &n, &k);
   for(i = 0; i < n; i++){
     scanf("%d", &A[i]);
   }
-
+  ans = binary_search(A, k, n);
+  printf("%d\n", ans);
 
   return 0;
-}
+}
\ No newline at end of file